ya know, guys i think xemnas IS TERRA. he has ALMOST none of MX inside him. this'll explain why:
1. he calls aqua's armor friend.
2. he is looking for the chamber of repose where ven is.
3. ( IMPORTANT THIS IS WHY HE MOSTLY ISN'T MX) xemnas wants KH correct? maybe he wants it because of this: "Hear me, Kingdom Hearts! It seems we must begin anew. Ah, but know this: I will give to you as many hearts as it takes. Mark my words! You can no more be complete without me than I without you. Heed me, Kingdom Hearts! Lend me your power, so that we may be complete!" he says this because he wants to use KH to bring his friends back, make himself whole again, ridding the universe of MX. and he says i will give you as many hearts as it takes signifying he will do anything to get his friends back and make everything the way it is supposed to be. i mean, he might have some of MX in him because i am betting MX's heart was infused with terra's soul, and when they split, some of MX remained. this could be explained by the fact he acts evil at some times, and very sad and faithful at others. so this is my theory, HOPE YOU LIKED IT.