I don't get why Xemnas wants Xion to absorb Roxas or Roxas to absorb Xion. The only reason that i can think of is to make one of them stronger which would protect the memories keeping Sora asleep better. Either way he would be losing a keyblade wielder which would half the amount of hearts collected, unless Xion's keyblade cannot collect hearts because it is fake.
I don't get why Xemnas wants Xion to absorb Roxas or Roxas to absorb Xion. The only reason that i can think of is to make one of them stronger which would protect the memories keeping Sora asleep better. Either way he would be losing a keyblade wielder which would half the amount of hearts collected, unless Xion's keyblade cannot collect hearts because it is fake.