what i think so far is....in the first game xehanort's heartless took ansem's name, in the trailer, we see an old man talking to terra about darkness or something of the like, and with the way terra looks, just like xehanort in the kh2 flashback, but with bbrown-ish hair...what i think, is that xehanort was terra's master, when terra and his friends defeated xehanort, he took his name, and xehanort, or terra, plunged into darkness, creating the games antagonists
now, with the ventus/roxas thing.... if you watch the trailers, near the end ventus says that terra needs to "erase him" and also, terra says to xehanort "what have you done to his heart?!" what i'm thinking.... is that somehow, ven's heart was linked with sora's, when sora's got taken in kh1, ven was released, though he was named roxas by xemnas since in the trailer as well, it sorta hints in a way that he can't remember anything, just like roxas.
[Edited by Elimon218, 6/4/2009 6:57:49 PM]