Gosh... [He catches his breath. THIS is probably going to take a while.]

Look, I don't really know that for sure. Roxas is... well, he's Roxas. I don't think there's anythin' quite like him in the history of the World. What I do know is that Ventus's heart went to sleep within Sora, and that's probably how Roxas ended up lookin' like Ven instead of Sora. That must mean they have some sort of connection, but what that is... sorry. Couldn't tell ya.