This is amazingly done. Both Xion and Riku seem completely in character. I like how Xion is somewhat unreliable, how she assumes things about Riku and about herself that may or may not be true. I liked your choice of limiting the POV to Xion, leaving Riku a bit of an enigma to the reader to. You kept him in his Days persona very well, too.

Good job. I'd like to see you try your hand at more canon KH stories like this. Not everything has to be blatant romance or AU.

This is gonna continue, right?
Because this is epic.

Oh It sounds intersting. I like your writing by the way.

COOL~!