Right, okay so, couple of things that need attention, so here goes...

Sezir, am I safe in presuming the "Dark Figure" is meant to be the same one everyone else was meant to see? If so, then bare in mind it's not meant to linger, and in fact only be there for like a split second.

Okay, Reap, I actually saw your sheet when it was first posted but have mostly been conflicted about it, hence my lack of response until now. First of all, if his world was one of the ones that blinked out and he was there at the time, then that means he's absurdly old or immortal or something of that nature, and I don't think such a thing fits in with this particular story (feel free to correct me on his age if I'm misunderstanding something, but that's what I took from the history). Secondly, and this is where I was most conflicted, is in regards to his sword. Now, I'm not claiming to know your intentions or anything, so I'll just apologize in advance for this, but the sword (to me, anyway) seems to just be a re-skinned Keyblade and I'm afraid it won't be feasible in this setting. In case you're unaware, Heartless [i]can[/i] be killed with conventional weapons, as evidenced by Final Fantasy characters being able to fight them off, so if you're worried about not being able to defend yourself, then don't be. Also, I have plot-related plans for how the party will eventually deal with Heartless and the Darkness in general and your sword kind of contradicts some of those plans, I'm afraid. Finally, one can't just spend centuries surviving in the Dark Realm. For one, it wouldn't stop him from aging, and secondly, just being in that Realm constantly runs you the risk of being consumed by Darkness. Ever wonder why Riku stopped using the dark portals? It's because the Other Side is so pure with Darkness that just briefly passing through it via Corridor of Darkness can be risky to one's Heart.