I was thinking about Terra and Xehanort and also Aqua. Please feel free to give your opinion, so here is my theory.
What if Terra is Xehanort from Kingdom Hearts II. I mean look at the hair, they have like the exact same hair style. The exception is that in the Birth By Sleep movie Terra's hair is like reddish. What if Terra becomes evil and takes Xehanort's name like Ansem took Ansem the Wise name. Remember, Ansem the Wise found Xehanort with his memories lost. Terra becomes Xehanort of KH2, eventually his Heartless and Nobody forms pop up(Ansem and Xemnas). We also have the assumption of the extra movie in KH2:FM+, where Xemnas goes into that secret room and is talking to that chaser armor, which appears to be Aqua's armor.
This is just a theory I thought of I dunno if this has already been considered, but it was just a thought.
What if Terra is Xehanort from Kingdom Hearts II. I mean look at the hair, they have like the exact same hair style. The exception is that in the Birth By Sleep movie Terra's hair is like reddish. What if Terra becomes evil and takes Xehanort's name like Ansem took Ansem the Wise name. Remember, Ansem the Wise found Xehanort with his memories lost. Terra becomes Xehanort of KH2, eventually his Heartless and Nobody forms pop up(Ansem and Xemnas). We also have the assumption of the extra movie in KH2:FM+, where Xemnas goes into that secret room and is talking to that chaser armor, which appears to be Aqua's armor.
This is just a theory I thought of I dunno if this has already been considered, but it was just a thought.