Hello there, I have my own opinion and theory about this. The translation is: "To Roxas, in what way do I appear now?" - Doesnt this mean Roxas should know who she resembles? That he already saw the person she looks like? In the trailer, there is a par, where Zexion shows KH1 Riku to Roxas, couldnt he show him Kairi as well and that would mean that she resembles Kairi now? If not, I vote for Aqua theory, but I just dont know how could Roxas notice who she is....I dont agree with Sora theory - she is of the same height as Roxas, it might not be seen well, but she is, and her mouth and voice is female for sure, and it didnt change a lot in my opinion....And by the way - Riku knows about Xion's true form - He tells her to return into her original form, so I think it has nothing to do with Aqua/Ven theory....he doesnt know anything about them.