[quote=@RokkuHoshi]
[@Gisk] He can start where everyone else does, he's just from Halloweentown.
[/quote]

How does he come to be there? Other worlds are not well known, there isn't really anyone besides keyblade wielders who travel between them. I'm trying to think of a way to make it work with the plot without stretching it too much. 

Since we're not planning to travel there, Halloween Town could very well have been destroyed, this would also give your character a similar motivation to the others. This works well with our first "world" that we visit, too. 

Minor spoilers, but the first place we appear is on a ship that has been charged by Auldus to travel the void between worlds and collect those who have survived destroyed worlds. When this ship collects us, your character could already be on it. 

EDIT: I started this post like "I dunno, man, it's a serious problem" and ended it like "actually, here's what we do."

EDIT Numero Dos: Also, your character could be a useful exposition tool, too. 

So the answer is yes, if you're okay with Halloween Town being bye bye.