User blog comment:RenaissanceReaper/PSASBR2/@comment-6992314-20130403180427/@comment-10603955-20130403204510

There's not really a connection, Nightmare has more in common with Sephiroth from KH. The only thing thats notable of connection is that they have guest characters in their games(so far, that's it).

Personally, I can't think of any good rival for Sora since there has never been a competitor to KH. There's that kid from Pagemaster but that's a movie.