Why hasnt anyonew said this yet? Vanitas isnt Sora's dad AND or Kairi's grandma, its Ven! Vanitas is Ven's extracted darkness, that's why in the first cutscene Master Xehanort is on Destiny Island with Ven unconscious in a sheet, he probably stole him while he while he was alseep then extracted his darkness for one of his theories, like maybe extracted the darkness from a keyblade weilder and... something... Or maybe he wanted to make a pure heart? And I'm not going to bring up the Fan-Serves in that cutscene, why did he have to be shirtless?! There's only 2 reasons I can think of, MX did tests, he was sleeping at home so he took his shirt off, MX took it off for reasons unknown/ pedobear alert.
ANYWAYS! I think maybe it involved Destiny Islands, like he was trying to unlock its keyhole, but it wouldn't... Maybe that's why he needed a pure-hearted keyblade weilder?
P.S in KH3 What do you think Sora and Riku's keyblades alt forms are? I mean I guess they might not have an alt for and or dont need it, sense Sora uses the Gummi Ship... Though Riku cant and or doesnt choice to use the Dark Corridors anymore, so he might get one... or travel the GUmmi ship as well...
P.S.S Sorry this is kinda long, I tent to ramble when it comes to KH, Im a Huge (NOT FAT!) Otaku, and KH is a very important and large portion of my life!