Really liked this. I think you catch Demyx's personality very well, as well as the conflict of trying to figure out exactly what Nobodies are - even when you are one. (Existing? No I'm not doing that either) Too cute!
Also kind of sad though, especially when we know what's going to happen to Demyx the next time he meets the Keyblade master. Poor woobie Demyx! This boy really needs a happy ending. sigh
Very well done though, thanks for sharing!