MarkXIIII

I noticed some things were somehow unclear and this leads to some confusion concerning DDD.
I revisited DDD and decoded to point out some things I noticed.
 
If you are interested in the laws of the KH universe, please domvisit my other thread in which I wrote an explanation of how Hearts, Nobodies and comcepts such as connected hearts, death or memories work.
 
 
In DDD we encounter some things that often get confused, this should clear things up.
 
 
DDD is the story of Soar and Riku's Mark of Mastery exam.
Yen Sid instructs them to UNLOCK 7 Sleeping Keyholes and as a side effect, X sleeping worlds would wake again.
 
KEYHOLES:
yen Sid's quest is to unlock 7 keyholes.
As Riku and Sora are in different parts if the worlds, they rarely unlock the same keyholes.
 
Sora's keyholes are:
 
Traverse town (1)
 
Cite
Grid
Prankster
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
Riku's are:
 
Traverse town (1)
 
Cite
Grid
Monstro
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
 
Anyway, there are more keyholes shown which are NOT sleeping keyholes but opening passages to the realm of sleep:
Destiny Islands
Mysterious tower
 
Both those worlds are not sleeping and the boys enter the realm of sleep at destiny islands.
Still, destiny islands is not a sleeping world (duh, we see it getting restored in Kh1)
Xehanort (robed figure) slips into the realm a t this point too, because he was present at the destruction of the isles (time travel law).
 
Yen sent the boys back to their 14/15 year old times because they should learn to wield a keyblade from scratch, but im sure you knew that.
 
Sora re-enters the realm from mysterious tower because traverse town is still there (presumably cuz it's needed there) and hence he can reunite with the dreameaters. (Though it is highly unlikely he can take them with him...)
 
 
So both boys unlock 7 keyholes and therefore fulfill the requirement of the exam.
 
 
Yen sid only spoke of 7 keyholes and never of 7 worlds. People got confused by this a lot but traverse had 2 holes and neither destiny islands, mysterious tower (music realm did, though) and the remnants of the world that never were sleeping worlds.
 
Sora and riku visited the 2 halfs of traverse and the other half on the second visit, therefore it can have 2.
The whole plot is confusing because they merely visit the world in a 1/2 dream each. The world dreams up what its places looked like, what its inhabitants acted like and so on.
This is why sora and riku meet people that should know them but don't, and why sora and riku meet people that act differently in their respective interactions with sora and riku.
 
It is most likely that those worlds will reappear in future games and then will finally get "propper" and linear storylines (and real bossfights - frollo anyone?)
But to do this they need to be restored and therefore we can guess which worlds got restored because of DDD:
 
Traverse Town: should be released from dream status but remains in realm of sleep so far because needed there. If need be in real world it will return there. It's likely the twewy gang will return to shibuya in khiii and traverse will return then. If this world appears where needed, then it never needed rescuing anyway.
 
Cite: likely restored
 
Grid: likely restored and accessible again from Radiabt garden Computer systems
 
Prankster / Monstro: likely reatored and maybe connected to jiminy-related storylines...
 
Musketeers: likely restored but unlikely to return as Mickey and friends lived there obly in their pasts... So it should be empty now or with new inhabitants
 
Realm of music: likely restored and under yen sid's control again and should be accessible again from mysterious tower. Might return with fantasia 2000 storylines...
 
 
All other worlds featured, destiny islands, mysterious, and twtnw, never needed rescuing and were onky used to open paths to the realm of sleep of even a sleeping heart precisely...
 
 
Lastly, there's been a theory that those worlds used to open pathways were safeguarded because they had a keyhole of sleep- ish keyholw opened there. Therefore, they got restored at the end of KH1 because of that.
In other words, the islands gpt restored for sure because sora and riku returned in ddd to make sure they will get restored but none of this makes sense...
The only thing that makes sense is that future-sent-back sora and riku took the raft which was missing in kh1 but still none of this makes sense because if the islands never were restored then they could not return there and traverse would have hosted kairi instead of returning her home...
 
 
 
Still, I just wanted to point out that DDD only speaks of the requirement to unlock (at least) 7 keyholes of sleep to return X worlds to the real worlds from the realm of sleep.
There is no word on how many worlds were/would have been restored and there is no real connection between the worlds visited and the keyholes. The worlds visited are mere dream-imaginations of the worlds rather than the physical wolrds themselves and some of the worlds featured are in the real world and twtnw is in the inbetween.
Fact is, sora and riku unlocked the required amount both and some if not all sleeping worlds returned to the real world. And by doing so, Riku gained the rank of mastery and the power to unlock a sleeping heart and sora gained the power to re-enter the realm of sleep.
And both boys should have gaibed some new "proper" keyblade skills only master-trained wielders can have gained.
 
I hope any of this makes sense as im traveling and its superlate here.
Sorry for errors and typos...

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

1) The word is naïveté
 
2) Sora IS serious when push comes to shove (crying a lot over KAiri and Riku, begging Saix, dispairing when everything seems lost...)
 
3) Sora is supposed to motivate the player to empathize with Sora, therfore Sora is supposed to be the more-or-less childish, silly, Rookie wielder who is growing better becasue THE one important thing he is serious about is his Friends.
 
4) Would you prefer SOra to give in to darkness already and die?

1) The word is naïveté
 
2) Sora IS serious when push comes to shove (crying a lot over KAiri and Riku, begging Saix, dispairing when everything seems lost...)
 
3) Sora is supposed to motivate the player to empathize with Sora, therfore Sora is supposed to be the more-or-less childish, silly, Rookie wielder who is growing better becasue THE one important thing he is serious about is his Friends.
 
4) Would you prefer SOra to give in to darkness already and die?

1) The word is naïveté
 
2) Sora IS serious when push comes to shove (crying a lot over KAiri and Riku, begging Saix, dispairing when everything seems lost...)
 
3) Sora is supposed to motivate the player to empathize with Sora, therfore Sora is supposed to be the more-or-less childish, silly, Rookie wielder who is growing better becasue THE one important thing he is serious about is his Friends.
 
4) Would you prefer SOra to give in to darkness already and die?

I noticed some things were somehow unclear and this leads to some confusion concerning DDD.
I revisited DDD and decoded to point out some things I noticed.
 
If you are interested in the laws of the KH universe, please domvisit my other thread in which I wrote an explanation of how Hearts, Nobodies and comcepts such as connected hearts, death or memories work.
 
 
In DDD we encounter some things that often get confused, this should clear things up.
 
 
DDD is the story of Soar and Riku's Mark of Mastery exam.
Yen Sid instructs them to UNLOCK 7 Sleeping Keyholes and as a side effect, X sleeping worlds would wake again.
 
KEYHOLES:
yen Sid's quest is to unlock 7 keyholes.
As Riku and Sora are in different parts if the worlds, they rarely unlock the same keyholes.
 
Sora's keyholes are:
 
Traverse town (1)
 
Cite
Grid
Prankster
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
Riku's are:
 
Traverse town (1)
 
Cite
Grid
Monstro
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
 
Anyway, there are more keyholes shown which are NOT sleeping keyholes but opening passages to the realm of sleep:
Destiny Islands
Mysterious tower
 
Both those worlds are not sleeping and the boys enter the realm of sleep at destiny islands.
Still, destiny islands is not a sleeping world (duh, we see it getting restored in Kh1)
Xehanort (robed figure) slips into the realm a t this point too, because he was present at the destruction of the isles (time travel law).
 
Yen sent the boys back to their 14/15 year old times because they should learn to wield a keyblade from scratch, but im sure you knew that.
 
Sora re-enters the realm from mysterious tower because traverse town is still there (presumably cuz it's needed there) and hence he can reunite with the dreameaters. (Though it is highly unlikely he can take them with him...)
 
 
So both boys unlock 7 keyholes and therefore fulfill the requirement of the exam.
 
 
Yen sid only spoke of 7 keyholes and never of 7 worlds. People got confused by this a lot but traverse had 2 holes and neither destiny islands, mysterious tower (music realm did, though) and the remnants of the world that never were sleeping worlds.
 
Sora and riku visited the 2 halfs of traverse and the other half on the second visit, therefore it can have 2.
The whole plot is confusing because they merely visit the world in a 1/2 dream each. The world dreams up what its places looked like, what its inhabitants acted like and so on.
This is why sora and riku meet people that should know them but don't, and why sora and riku meet people that act differently in their respective interactions with sora and riku.
 
It is most likely that those worlds will reappear in future games and then will finally get "propper" and linear storylines (and real bossfights - frollo anyone?)
But to do this they need to be restored and therefore we can guess which worlds got restored because of DDD:
 
Traverse Town: should be released from dream status but remains in realm of sleep so far because needed there. If need be in real world it will return there. It's likely the twewy gang will return to shibuya in khiii and traverse will return then. If this world appears where needed, then it never needed rescuing anyway.
 
Cite: likely restored
 
Grid: likely restored and accessible again from Radiabt garden Computer systems
 
Prankster / Monstro: likely reatored and maybe connected to jiminy-related storylines...
 
Musketeers: likely restored but unlikely to return as Mickey and friends lived there obly in their pasts... So it should be empty now or with new inhabitants
 
Realm of music: likely restored and under yen sid's control again and should be accessible again from mysterious tower. Might return with fantasia 2000 storylines...
 
 
All other worlds featured, destiny islands, mysterious, and twtnw, never needed rescuing and were onky used to open paths to the realm of sleep of even a sleeping heart precisely...
 
 
Lastly, there's been a theory that those worlds used to open pathways were safeguarded because they had a keyhole of sleep- ish keyholw opened there. Therefore, they got restored at the end of KH1 because of that.
In other words, the islands gpt restored for sure because sora and riku returned in ddd to make sure they will get restored but none of this makes sense...
The only thing that makes sense is that future-sent-back sora and riku took the raft which was missing in kh1 but still none of this makes sense because if the islands never were restored then they could not return there and traverse would have hosted kairi instead of returning her home...
 
 
 
Still, I just wanted to point out that DDD only speaks of the requirement to unlock (at least) 7 keyholes of sleep to return X worlds to the real worlds from the realm of sleep.
There is no word on how many worlds were/would have been restored and there is no real connection between the worlds visited and the keyholes. The worlds visited are mere dream-imaginations of the worlds rather than the physical wolrds themselves and some of the worlds featured are in the real world and twtnw is in the inbetween.
Fact is, sora and riku unlocked the required amount both and some if not all sleeping worlds returned to the real world. And by doing so, Riku gained the rank of mastery and the power to unlock a sleeping heart and sora gained the power to re-enter the realm of sleep.
And both boys should have gaibed some new "proper" keyblade skills only master-trained wielders can have gained.
 
I hope any of this makes sense as im traveling and its superlate here.
Sorry for errors and typos...

I noticed some things were somehow unclear and this leads to some confusion concerning DDD.
I revisited DDD and decoded to point out some things I noticed.
 
If you are interested in the laws of the KH universe, please domvisit my other thread in which I wrote an explanation of how Hearts, Nobodies and comcepts such as connected hearts, death or memories work.
 
 
In DDD we encounter some things that often get confused, this should clear things up.
 
 
DDD is the story of Soar and Riku's Mark of Mastery exam.
Yen Sid instructs them to UNLOCK 7 Sleeping Keyholes and as a side effect, X sleeping worlds would wake again.
 
KEYHOLES:
yen Sid's quest is to unlock 7 keyholes.
As Riku and Sora are in different parts if the worlds, they rarely unlock the same keyholes.
 
Sora's keyholes are:
 
Traverse town (1)
 
Cite
Grid
Prankster
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
Riku's are:
 
Traverse town (1)
 
Cite
Grid
Monstro
 
Traverse Town (2)
 
Musketeer
Fantasia
 
 
 
Anyway, there are more keyholes shown which are NOT sleeping keyholes but opening passages to the realm of sleep:
Destiny Islands
Mysterious tower
 
Both those worlds are not sleeping and the boys enter the realm of sleep at destiny islands.
Still, destiny islands is not a sleeping world (duh, we see it getting restored in Kh1)
Xehanort (robed figure) slips into the realm a t this point too, because he was present at the destruction of the isles (time travel law).
 
Yen sent the boys back to their 14/15 year old times because they should learn to wield a keyblade from scratch, but im sure you knew that.
 
Sora re-enters the realm from mysterious tower because traverse town is still there (presumably cuz it's needed there) and hence he can reunite with the dreameaters. (Though it is highly unlikely he can take them with him...)
 
 
So both boys unlock 7 keyholes and therefore fulfill the requirement of the exam.
 
 
Yen sid only spoke of 7 keyholes and never of 7 worlds. People got confused by this a lot but traverse had 2 holes and neither destiny islands, mysterious tower (music realm did, though) and the remnants of the world that never were sleeping worlds.
 
Sora and riku visited the 2 halfs of traverse and the other half on the second visit, therefore it can have 2.
The whole plot is confusing because they merely visit the world in a 1/2 dream each. The world dreams up what its places looked like, what its inhabitants acted like and so on.
This is why sora and riku meet people that should know them but don't, and why sora and riku meet people that act differently in their respective interactions with sora and riku.
 
It is most likely that those worlds will reappear in future games and then will finally get "propper" and linear storylines (and real bossfights - frollo anyone?)
But to do this they need to be restored and therefore we can guess which worlds got restored because of DDD:
 
Traverse Town: should be released from dream status but remains in realm of sleep so far because needed there. If need be in real world it will return there. It's likely the twewy gang will return to shibuya in khiii and traverse will return then. If this world appears where needed, then it never needed rescuing anyway.
 
Cite: likely restored
 
Grid: likely restored and accessible again from Radiabt garden Computer systems
 
Prankster / Monstro: likely reatored and maybe connected to jiminy-related storylines...
 
Musketeers: likely restored but unlikely to return as Mickey and friends lived there obly in their pasts... So it should be empty now or with new inhabitants
 
Realm of music: likely restored and under yen sid's control again and should be accessible again from mysterious tower. Might return with fantasia 2000 storylines...
 
 
All other worlds featured, destiny islands, mysterious, and twtnw, never needed rescuing and were onky used to open paths to the realm of sleep of even a sleeping heart precisely...
 
 
Lastly, there's been a theory that those worlds used to open pathways were safeguarded because they had a keyhole of sleep- ish keyholw opened there. Therefore, they got restored at the end of KH1 because of that.
In other words, the islands gpt restored for sure because sora and riku returned in ddd to make sure they will get restored but none of this makes sense...
The only thing that makes sense is that future-sent-back sora and riku took the raft which was missing in kh1 but still none of this makes sense because if the islands never were restored then they could not return there and traverse would have hosted kairi instead of returning her home...
 
 
 
Still, I just wanted to point out that DDD only speaks of the requirement to unlock (at least) 7 keyholes of sleep to return X worlds to the real worlds from the realm of sleep.
There is no word on how many worlds were/would have been restored and there is no real connection between the worlds visited and the keyholes. The worlds visited are mere dream-imaginations of the worlds rather than the physical wolrds themselves and some of the worlds featured are in the real world and twtnw is in the inbetween.
Fact is, sora and riku unlocked the required amount both and some if not all sleeping worlds returned to the real world. And by doing so, Riku gained the rank of mastery and the power to unlock a sleeping heart and sora gained the power to re-enter the realm of sleep.
And both boys should have gaibed some new "proper" keyblade skills only master-trained wielders can have gained.
 
I hope any of this makes sense as im traveling and its superlate here.
Sorry for errors and typos...

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

Imagine how awesome KHIII could have been if it skipped from CODED right to KHIII:
 
(OLD) master Xehanort returns and wants to recreate a Keyblade war by recruiting many Disney and Final Fantasy villains besides some new Original Character bad guys.
 
Yen Sid leads his army consisting of Sora, Riku, Mickey, Donald, Goofy, Aqua and Ven, they clash and the good guys are assisted by some new Original characters that are drawn into the war.
 
Sora is the only main character and travels to many different worlds with Donald and Goofy. At certain fights he gets help from Mickey and the others like in KH2. Drive forms are back and Sora can use the original 5 but also gains new ones.
 
Reaction commands are more prominent and it is possible to enter command styles this way.
Sora can summon actual people like in KH1 rather than out-of-place roller-coasters and parade floats.
 
 
New Worlds include
“Tangled”,
“Frozen”,
“Duckburg” (whooo-oo),
“Shibuja”,
“Louisiana Bayou (Princess and the Frog)”,
“Treasure Planet”,
“The Black Cauldron”,
“Bambi’s forest”,
“Jungle Book”,
“101 Dalmatians” (guiding  Dalmatians while fighting Jasper, Horace and Cruella!!!),
"Pocahontas Jamestown and Riverlands" (Native Tribes Sora but I see Disney causing troubles due to political correctness)
 
 
Vastly extended worlds return with new storylines:
“Radiant Garden”,
“Twilight Town” (Hayner Olette Pence!! ),
“Traverse Town”, “Destiny Islands” (finally playable again, maybe even first world!),
“Keyblade Graveyard”,
“Kingdom Hearts” (we finally get to see it),
“100 acre wood” (always welcome to chill out at and surely cute with new graphics),
“Port Royal” (Plot of Pirates 4 and return of merman Sora fighting an underwater battle against evil mermaids and sharks!),
“Never Land” (mainlands, goofing with lost boys and fighting Hook is always fun as well as FLYING!!),
“Olympus coliseum” (fighting ALL of the Titans!),
“Land of Dragons”
“Beasts Castle”
“Dwarf Woodlands”
All of the princesses of light’s worlds actually with awesome quests to save them all from Xehanort’s minions who want to capture them.
 
 
Sora wants to find a way to get to Xehanort’s secret hideout and he has to fight Disney villains in their respective worlds who act as guardians for Xehanort's plans. More and more new bad guy characters interfere with Sora's paths and he finds out where Xehanort is hiding.
 
As he approaches the Keyblade graveyard he fights Xehanort who has some new tricks and spells and Sora is assisted by several characters as party members. Imagine Sora, Riku and Aqua against Xehanort's ultimate Dragon-like form. Donald and Goofy protect Kairi and the princesses of heart back at Mysterious tower/ twilight town and Kairi especially fights off an army of heartless invading the tower.
 
Xehanort pulls a final trick: he found indeed a way to unlock Kingdom Hearts.
Then He threatens to kill Sora, all other characters are locked out and Sora has to fight a final fight before losing to Xehanort. Eventually Sora is almost lost and Yen Sid fights and defeats Xehanort for good.
 
Anyway there ARE some losses, Ven dies as do two of the 4 new characters and Sora almost dies too.
 
Sora recovers and Kairi confesses her Love for him in fear he might die. Masters Aqua, Mickey and Riku and (now-again) Master Yen Sid combine their Curaza spells but Sora faints and only Kairi can save Sora with a Kiss of true love.
 
Everything is fine, everyone returns to their home worlds.
Yen Sid trains one of the new Characters to wield the keyblade.
 
Sora, Riku and Kairi return to Destiny Islands and Kairi and Sora are finally together. Riku also brought another girl he met on their journey.
 
Mickey, Pluto, Donald and Goofy return to Disney Castle /Town and are happily welcomed by Minnie and Daisy.
 
Jiminy goes back to Pinocchio's world.
Aqua returns to the now-restored Land of Departure and examines Yen Sid's students for the Mark of Mastery. She also built a memorial for her fallen friends Ven and Terra.
 
 
THE BEST thing of KHIII could be its predictability. Deaths like Ven’s would come surprisingly but the sheer technical and visual superiority of the game combined with the final loss of Xehanort we are yearning for yould be the biggest strength of the game.
 
 
 
And a classical Disney-style Ending scene:
First we see all those ending scenes I mentioned above, and then during the credits all the Disney endings are played like in previous games.
Then the final scene:
Riku and his girl are leaning against the Paopu tree on Destiny islands, hugging and Kairi is seen fishing a bottled message out of the water by the docks. (a new raft is seen there too!)
Kairi opens the bottle and is surprised the letter is addressed to her. She reads the letter out loud  and finds out it’s from  Sora. The letter includes some poem that is similar to Kairi’s letter that saved sora in KH2 and ends with something really romantic/tacky like this:
 
We can see the end of the letter:
 
[…] Kairi,
You are my One Sky, my destiny.
I’ll always be with you
And I’ll always keep this promise.
[yours truly, Sora ]
 
Beneath the text we see Sora drew the Paopu fruit sharing he drew on the stone wall in the secret cave. (and his drawing skills have not improved a bit, haha)
 
Then we see Sora sneaking up behind Kairi and covering her eyes with his hands from behind.
Due to her eyes being covered, she stops reading but Sora finishes “I’ll aways be with you…”
She smiles, turns around and her smile becomes radiant when she sees it’s indeed Sora.
Then the camera turns behind the two of them with a wonderful view of the glittering golden sea behind them. The light gets more intense and for a moment we see Naminé and Roxas smiling at each other and Naminé sheds a tear that continues running down Kairi’s cheek. Sora, having watery eyes himself, wipes the tear off her cheek.
 
Finally we turn to a Disney fairy tale movie-like close up showing their faces getting closer, their eyes closing and finally, accompanied by Mrs. Shimomura’s subtlest yet most majestic tunes, the final Kiss of true love.
 
Fade and then the golden letters “The End” appear before the animated logo of Kingdom Hearts III materializes and the music fades out.
 
 
 
The battle report screen shows the usual record data and features a most beautiful artwork including all characters in the series, similar to the one in the KH2 Final Mix.
 
 
 
Hope you enjoy this theory and despite I fear KHIII won’t be as great because it’s been hyped and idolized for too long now, and DDD did a major part in downgrading its potential, I’ll get it just for the growing possibility of Sora and Kairi finally getting together!!
 
Feel free to add you own ideas!

Thank you so much!! :D
 
Well, I considered myself quite good in KH knowledge too - before I met you that is...
 
Please tell me you eye color is NOT Xehanort-yellowish!?

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

Xehanort has a special heart as it seems:
 
This is Xehanort Reduced to just a Heart / Heartless:

 
In BbS:
 
Xehanort transfers his heart to Terra after releasing it:

But it looks just like a heart of Pure Light!!
 
In DDD:
 
Xehanort does this little trick with his Keyblade and glowing magic fingers:

 
And the he releases (at least a fraction of) his heart and shoots it over to implant it into Sora.

And yet again his heart's fracture has the appearance of a pure heart of light...
 
 
However:
He can also do this neat trick and summon this orb that gathered Kingdom Hearts in BbS:

I think this would personally fit better for his heart (flaming darkness)
 
 
I wonder what is the reason behind this. The shapes and concepts of heart are consistent throughout the whole series!
Why would Xehanort's heart be different?
Here's the cinematic version of that scene:
 
THIS is what I imagined Xehanort's heart to be like:

Here are pictures of what hearts look like in the series:
 
Regular Hearts:
 
A random woman' shears is stolen:

 
Hearts apprentice Xehanort experimented with:

 
 
Hearts of pure light (natural as for the PoH or artificially for Ven):
 
Aurora's heart:

 
Sora about to take in Ven's heart:

In case anyone is wondering WHERE in he world I got the Kairi-Demyx connection, 
I took it from the semi-canon manga series.
 
Personally, I see the manga just as semi-canon. Nomura has taken several Manga-exclusive scenes into account in Final Mixes (just like the novel series)
 
anyway the points mentioned in the manga and novels are minor but I still included this connection:
 
http://kh13.com/zenphoto/manga/kingdom-hearts-ii/chapter-45/061.png.php
 
for the mere reason I think there's more to Demyx than meets the eye.
For example, he is one of the most strange Nobodies, showing several heart-like traits 
Laziness, pleasure, anxiety, fear, uncertainty, friendhip
 
due to his interactions with Roxas, Sora and Kairi, he was able to initiate a nurturing of a heart.
And I think he really sees Roxas as a friend cuz he is interacting with him in Days in a more friendly manner and wants to get him back in KH2. Also, he is friendly toward Kairi: addressing her as "Princess" and "Miss Kairi".
 
Make sure you check out this little Demyx and Kairi centered episode, it's hilarious!
(and I almost feel angry because Sora killed Demyx)

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

+ a HUGE THANKS to King Mickey  who stirred me in the right direction and helped me find the last clue that hearts fade when an existence dies!!!
THANK YOU!!!

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

And All characters can return easily except Roxas, Namine and Xion.
 
Namine might come back easily by releasing her heart from within Kairi's.
Roxas would have to get a completely new heart in order to become his own person.
Maybe Roxas Even grew his own heart "around" Ven's heart...? (in this unlikely case Sora is Harboring 3 hearts currently)
 
Xion might have had a heart but as she really died and faded, it's hardest getting her back cuz one need to get her a body and heart...
 
 
So concluding one can say that these people are the only three that "deserve" to be their own persons - whcih is why Sora said so in DDD - precisely because They are NOT Nobodies, like shadows of their original selves, but vastly different individuals who din't even remember hwere they came from!
 
Thank you very much!!
I  spent 100s of hours and 100s of pages of scribblings and notes just to come to this conclusion.
At first I thought DDD didn't make any sense but now I see the whole picture, haha.

Sprawled over several threads I collected all theories on how all KH heart theories go together and it finally makes sense:
 
 
 
 
 
 
 
1 Somebody = 1 Heart + 1 Body + 1 Mind / Soul
 
Example: Riku
 
 
 
1 Heartless = 1 Heart (stolen)
 
Example: Soldier (Emblem Heartless)
 
or
 
1 Heartless = 0 Heart
 
Example: Shadow (Pureblood Heartless)
 
 
 
1 Nobody = 1 Body
 
Example: Dusk
 
 
 
1 Sentiment / Will = 1 Mind / Soul
 
Example: Lingering Sentiment (Terra’s Will)
 
 
 
1 Unversed = 0 0 0 (hence not well versed with life!)
but negative emotion and pure darkness involved
(also memories?)
 
Example: Flood
 
 
 
There's also the concept of memories which is closely related to the mind and heart.
 
 
 
 
Special Cases:
 
 
 
Special Somebody: 2 Hearts + 1 Body + 1 Mind / Soul
 
Example: Sora
 
 
 
Special Somebody PoH: Pure Light Heart + 1 Body + 1 Mind / Soul
 
Example: Snow White
 
 
 
Special Somebody PoH: 1 Body + 1 Mind / Soul (Heart does not fade into Darkness)
 
Example: Kairi
 
 
 
Special Heartless Sora: 0 Heart(s) + 1 Mind /Soul
 
Example: Sora
 
 
 
Special Heartless Ansem: 1 Heart + 1 Body + 1 Mind / Soul
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul
 
Example: Zexion
 
 
 
Special Nobody: 1 Body + 1 Mind / Soul [+ 1 Heart]
 
Example: Axel
 
 
 
 
 
So when a Somebody loses his heart he creates a heartless. The heart fades into darkness.
The being left behind is a manifestation of the darkness the heart fades into.
The classic form of a heartless has no heart and has a void form and no mind (classic case of a shadow creation).
These heartless try to "steal hearts" (presumably of people - thus creating more heartless - and if they get the chance to, also those hearts lingering in the darkness).
If a heartless manages to get a heart, this heart is released when he gets destroyed (Emblem Heartless).
High Heartless can have a form and even carry over the mind (Seeker of Darkness)
 
The body that is left behind turns into a mindless shell (classic case of a dusk creation)
 
When the Somebody had a strong mind, this person also can create a high nobody (Org. XIII)
therefore the persons left behind will and body from a new existence.
This existence might be able to grow a new heart (details fruther down).
 
 
 
The concept of "body" I speak of refers to an "own" body as a person, similar (roxas) or identical to the regional Somebody (Axel).
While pureblood heartless or unversed can easily be imagines as lacking a body, higher heartless also lose their original forms and are therefore counted as formless or bodiless.
Dusk and other lower nobodies are counted as having a body and yet this body gets changed. While higher nobodies can easily be imagined as having a bodily form, those lower nobodies (like dusks) still have some kind of shell-like body because they are what is left of a person's body-shell in the first place.
This theory is also supported by the fact that nobodies (no matter whether humanoid or dusk) are higher beings than heartless because they consist certainly of at least one part (body) and this tries to from a second component of existence (heart) and higher ones even a will (making them like a complete being just the original being and heart is gone). So Nobodies have 1 or 2 or all 3 parts.
Heartless don't have to have either to exist and lack minds in 99% of cases, and a body.
And heartless lack their own hearts!
We do not know if a pureblood heartless can change into an emblem heartless by stealing a heart or if the heartless has to stew a heart before manifesting from the darkness.
Another point is that heartless STEAL hearts and therefore do not have their own hearts!
Therefore they do not have control over this heart (thus they act like beasts) because they contain a random heart.
 
Ansem, Seeker of Darkness, is the notable exemption because he gave up his heart on purpose and therefore could exist. He released his heart which didn't get swallowed by darkness but he regained control over it (and as a bodiless form he could initiate time travel - and this is the reason why not everyone can do it). So he was reduced to heart and mind. Xemnas was formed with mind and body. Therefore Ansem was almost complete again after regaining his body with Riku's help after possessing him and gathering strength in the process.
 
 
 
It depends whether memories are also part of the mind or not.
Too little is known about minds- like if memories are carried over as part of the mind (like most regular high nobodies) or not (roxas) and if this is part of the mind at all.
 
Also the case of sentiments is not completely probed yet.
 
Basically, minds are entities of self-consciousness (lingering sentiment) but memories are closely connected and even more important!
 
So memories are definnitely engraved in the hearts in any way [Naminé says so] and therefore if the heart is lost memories can also stick to minds as a backup (therefore Lingering sentiment remembers Ven and Aqua lost and hatred for Xehanort although Terra's heart is lost to Xehanort) (or each high Nobody rememebers without having a heart)
 
To exist on its own, aka to form a sentiment, a mind has to be extraordinarily strong!
And therefore we can say a mind is "merely" a concept of self-reflexion/awareness and existence.
It's easier to think about it this way than to call is soul because souls are surely harder to vanquish and recreate from scratch than the mind/awareness.
Xehanort (apprentice) is even seen to "split" his will, as both his Heartless (Ansom) and Nobody (Xemnas) are 100% self-conscious each and acting as 2 individuals. [You see, it's rather a concept of self-awareness as a being rather than a soul concept]
 
And actually it does not matter Lea's mind got transformed when turned into Axel. And it doesn not make any difference if Axel's mind fades completely and Lea's mind is recreated or if Axel's mind is just turned back into Lea's.
The main point is that Lea was self-consious as Lea then also as Axel and then again also when becoming Lea again. [Maybe even slightly different each time (Axel is definitely more reluctant than Lea due to his missing heart in the begining - as well as Xehanort's manipulations) but It stays the SAME guy! Same memories- Proof: "Got it memorized?"]
And this is also the main reason this concept plays a minor role in the series.
 
 
 
 
If a Somebody dies, the Heart, Body as well as Mind die too!
 
We also know that the heart is the CORE of existence and one only dies when the (original) heart dies or fades.
Ansem was reduced to just a heart without a body (and existence hence mind?)
 
In the worst case a weak somebody is reduced to a heart which is stolen by a formless shadow and mind as well as body fade. But the person is not dead until the heart dies and still can be saved.
 
In order to erase someone completely from existence in the KH universe one would have to steal the person's heart. then distroy the remaining nobody (and if it's a higher nobody it's will) so there is no chance (or known way) the person's body could be restored. Next one would have to vanquish the heartless holding this heart and release the heart. The heart has nowhere to return to and would fade into darkness again or get caught up inside another heartless so one has to either gather it using a Keyblade or other device.
As the last step one would have to destroy the heart which is now the floating essence of the person's existence as neither body, nor will exist. With the heart the existence as well as the memory would be erased and the person is gone forever.
But basically, a heart is never lost for good, unless it is specifically targeted and destroyed like in the case I just mentioned.
 
In some part of the reports, the soul is mentioned with a connection to the mind and heart.
So when someone really dies in KH series,
 
1) Body
2) Mind
3) Heart
 
Die and therefore
 
4) memories
5) soul
 
Die with them and the person is completely annihilated.
 
 
 
If a Heartless dies, the Heart gets released
but it will return to darkness and might even get captured by yet another heartless
unless released with a "key" (to be gathered at a central place a.k.a. Kingdom Hearts [of hearts] )
 
If a pureblood heartless dies, the darkness manifested fades away.
 
 
 
If a Nobody dies, The Body and Mind die [and the Heart dies]
 
 
 
 
 
Therefore:
 
 
 
1) The Princesses of Heart must be protected at all costs in order to protect their lights, cuz if they die, the light dies!
 
 
 
2) Axel and all other Nobodies GREW or nurtured their own hearts, of course!! (or at least partly or fragments of hearts) Therefore they were able to feel and act.
 
This process of growing a heart is a natural process of the body of the original Somebody to replace what has been lost. It is unclear and unlikely a heart can be regained completely on this way. (these hearts "grow" so Nobodies can have fractions of hearts)
 
This process has to be initiated by the connection with a REAL heart.
Axel's case is the prime example for Sora's heart touching a Nodody and therefore initiating the growth of a heart. Axel is surprised he is enjoying his schemes in Castle Oblivion and states Sora 'must have rubbed off'. In KHII Xemnas confirms Sora's influence.
 
Some other Nobodies in the Organization also grew hearts (or heart-buds) in order to her able to enjoy things (larxene - she enjoys pain?) [Luxord's love for his games; Demyx's music and fear].
 
 
 
WHEN Axel died, his body, mind and HEART died.
 
And then LEA got restored with LEA's Heart (this is why the heartless has to be felled before this to release the original somebody’s heart)
 
 
 
LEA: 1 Body, 1 Mind, 1 Heart
 
 
 
Lost his heart and created:
 
 
 
AXEL: 1 Body (Leas Body therefore he looks the same), 1 Mind
 
 
 
Shadow (presumably): Lea’s Heart
 
 
 
 
 
Axel grew a new heart and therefore was a complete incomplete being.
 
 
 
Axel: Body, Mind, Heart (of facture of a heart)
 
 
 
Shadow is felled: Lea’s heart is released.
 
 
 
Axel died: Axel’s body, Mind and Heart fade away.
 
 
 
But
 
 
 
Lea is restored with his original Heart which is now free and his mind and body are restored too.
 
[There is also a theory that says that the mind never fades until the somebody dies but the mind is rather carried over to the next high existence, so Lea's got definitely transferred over to Axel but it is unclear whether Axel's mind dies and Lea's got recreated or if Axel's got restored as Lea's but it doesn't matter because the memories are the most important part and they are part of heart and mind!]
 
[Roxas' case if different alltogether and contradicts the main mind theory cuz Roxas, just like Naminé, has his own mind and if he were to die, his body, his mind (and Ven's heart) were to die and fade away - and how Sora would have been affected is unclear - mostly through his memories; also Ven's reaction to this fatal case is unprobed]
 
 
 
 
 
 
Therefore, it does not matter whether nobodies grew their own hearts cuz if they died these hearts faded away anyway just like their existence and the original being got restored.
 
 
 
 
 
 
 
HOWEVER:
 
 
 
This is not true for
 
 
 
SORA – ROXAS (Special Origin + Heart transfer +Reunion)
 
KAIRI - NAMINE (Special Origin + Reunion)
 
 
XION (did she ever have a heart?)
 
 
 
 
 
AS IN DDD: Data DiZ states that Sora has been able to reunite with his Nobody without destroying him!
 
Axel died in order to revive (as) Lea.
Roxas never died, neither did Namine.
 
 
Assuming Roxas didn’t have the need to grow a heart cuz he had Ven’s how could he ever be restored as an own person as he is the only nobody completely without an own heart??
 
Do you think Xion grew a heart too? If so her heart most likely faded away too.
 
If Namine grew a heart, Kairi harbors it so namine would be easier to rstore as her own existence.
 
Poor Roxas! Seems like he is the biggest nobody of them all!
[Roxas might very well have started growing his own heart because he had Ven's heart inside of him. This heart was sleeping (which supports the thesis why he might have grown an own heart in the first place) but complete and therefore he could cry as the only nobody.]
 
 
 
So according to all this Axel is Lea while not being Lea. So Axel really died while really being restored as Lea. So if Roxas ever got his own existence, the Axel/Lea he were to meet was not the same Axel he knew.
 
 
 
So it is a sad story after all.
 
 
Therfore, truly all (org. XIII) nobodies (including their bodies and possible hearts) are gone and their original selves are back!!
This is why Lea does not have Axel's cheek marks!!
 
And lastly:
 
1) It would be impossible to have Axel coexist with Lea
because Axel HAD to die in order to Revive Lea
(cuz lea was gone unless somone would have restored him from his shadow / heartless form but there was no special heart involved like in sora's Kairi's case)
 
2) It would have been unneccessary to have Lea AND Axel cuz they are 1 and the same existence!
and I don't think this would have been scientiffically possible (again no Pure light involved)
 
3) The Special Case of Namine and Roxas is different cuz they do not only coexist with their somebodies
but they also are their own existences and identities right from the beginning (like Mr. Nomura and DiZ stated since KHII they are most special Nobodies!!)
 
4) In case anyone is wondering WHO and WHY almost all characters that show up in DDD behind Sora in his "my friends are my power" statement against Xigbar, or Xemnas or Xehanort Junior (don't rmemebr, sora just states he's proud to be part of something bigger) These Are ALL heart connected to Sora AND Ven’s Heart! Either because they have close connections through friendship or love, or because they have somehow connected hearts
My Only Question was: WHY is Naminé missing as the only one, all other main Characters are present.
The reason is: Naminé is connected to Kairi’s Heart. It would be OK to include Naminé in this list but she is only connected to Sora’s heart in a “once removed instance”.
 
Finally here is a list of everything connected to Sora’s Heart:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
Ties Of Friendship:
Riku
Donald
Goofy
(Mickey)
 
Connected Hearts:
Roxas
[Xion] (in case Roxas Has a Heart she is a tie of friendship of Roxas’ heart; but still included as she is/was a replica of sora directly that was influenced by Sora’s memories of Kairi)
Ven
 
Ven is the Connection cuz his own heart has other connections:
 
Ven’s Heart:
 
Ties of Friendship:
Aqua
Terra
Mickey (I think Mickey is even featured in his BbS outfit, hence the inclusion here)
 
 
Naminé is connected to Sora because Sora harbored KAiri’s heart during KH1.
When Releasing his and Kairi’s Heart both Roxas and Naminé were born.
For this reason and because of this connection Naminé has pwers over Sora (or more precisely his memories).
 
As Kairi’s Heart is no longer directly with Sora’s Naminé should be connected in a second instance like this:
 
Sora’s Heart:
 
Ties of Love:
Kairi
 
[…]
 
Kairi’s Heart:
= Pure heart of light
 
Ties of Love:
Sora
 
Ties of Friendship:
Riku
Selphie
 
Wakka
Tidus
 
Princesses of Heart
Demyx
 
Connected Hearts
Naminé
 
 
Naminé could also be included in a
“Memories connection” section for Sora
Just like Xion can be included in this category for kairi.
 
 
Lastly
 
Roxas is the most complicated of them all because we don’t
Know for sure whether he has a heart on his own:
 
Roxas’ Heart:
= nonexistent???
= Ven’s Heart
 
Ties of Love:
Naminé
 
Ties Of Friendship:
Axel
Xion
Demyx (he talks quite often about him compared to other members)
Hayner
Pence
Olette
 
Furthermore:
Genie
Zero (Jack’s dog)
(Riku?)
 
Ties of connected hearts:
Ven
Sora
[Xion] (depending on what happened to her existence)
 
And to round it up:
 
The memory connections for Roxas include:
 
Naminé (therefore shw and DiZ were able toreimplant the lost (Xion) memories at the beginning of KHII)
Kairi (due to the closeness of Sora’s And Kairi’s heart at the creation of Naminé and Roxas all 4 of them are closely related and therefore wehen Naminé restored Sora’s Memory through Roxas in KHII Roxas was able to connect with Kairi and help her remember Sora’s name)
 
 
These are just tiny extracts from all the connections of hearts; I forgot too many Ties of friendship (Selphie, Tidus, Wakka, Hayner, Olette, Pence) but I think I covered the most prominent.
 
 
End of Theory :D
 
PS: I rewrote some parts and edited several unclear passages. I hope everything is more precise now.

And All characters can return easily except Roxas, Namine and Xion.
 
Namine might come back easily by releasing her heart from within Kairi's.
Roxas would have to get a completely new heart in order to become his own person.
Maybe Roxas Even grew his own heart "around" Ven's heart...? (in this unlikely case Sora is Harboring 3 hearts currently)
 
Xion might have had a heart but as she really died and faded, it's hardest getting her back cuz one need to get her a body and heart...
 
 
So concluding one can say that these people are the only three that "deserve" to be their own persons - whcih is why Sora said so in DDD - precisely because They are NOT Nobodies, like shadows of their original selves, but vastly different individuals who din't even remember hwere they came from!
 
Thank you very much!!
I  spent 100s of hours and 100s of pages of scribblings and notes just to come to this conclusion.
At first I thought DDD didn't make any sense but now I see the whole picture, haha.

Um. You just like turned KH into a Science thing.
 
But anywho, I agree with your idea fully.

Hahaha, fair enough.
 
But still, Sora+Kairi is predestined!
http://www.youtube.com/watch?v=6qlfyFq_PEg
 
and this is only Part 1, haha
 
 
Anyway, granted, Mr Nomura is known for coming up with unconventional solutions, but still, I'm almost certain they'll get together in KHIII!!
 
Besides, what is the alternative? Riku? Nah!
 
Although, Nomura-san would get huge enjoyment out of throwing all those shippers off track with something like this:
 
Sora, Riku and Kairi return to Destini Islands Main Isle.
Riku and Sora are welcomed by their Moms while Kairi walks off holding hands with her boyfriends.
 
This would 100% fit Nomura logic:
*fans don't expect this
*it's so off it's actually possible
*a new character is ontroduced fans keep wondering WHERE he has been all this time.
 
Hahaha, just kidding,
Sora+Kairi is gonna happen. Period!