Once upon a time in a little island world, there was a redhead girl and the two boys who loved her; and when she lost her heart one boy travelled the worlds to find her (the other gave himself to the Darkness in order to get her back). When the first stabbed himself with the second's sword to unlock her heart, the memory witchling and heartless Keybearer emerged (prompting an impromptu game of Backstab Bonanza). Only the redhead girl was never real and none of this ever happened. Instead…
Riku had always always always wanted to leave the islands (because there had to be more to this world than this and he was determined to find it), but it was still a shock when he climbed through the window to Sora's room, shouting, "C'mon, Sora, I've found a way out!"
And so they both ran through the Door with their already-packed bags (because there was no common-sense redhead girl to mention that giant swirling Doors of pure evil were generally not things to go near). In the corner of Sora's mind, a masked boy was laughing in triumph as the confused Keyblade tried to work out what it was supposed to do if both its chosen Wielders ran unknowingly into the Darkness.
"I don't need you," Riku said impatiently, "I've got Sora. And I've already told you to quit following me- now go away!"
"We can't," the duck squawked, stomping a foot in annoyance. "The King says we've got to follow the Keyblade!"
At his side, the dog-thing nodded firmly. "A'hyuck, that's right!"
"Are you sure they can't come with us?" Sora asked hopefully, but Riku shook his head.
"No! We don't need them- we've got Keyblades, which means we are supposed to, I dunno, save the worlds or something. Not them."
Sora still looked unconvinced, but didn't protest further. "Then c'mon, we've learned what Leon's willing to teach us, we learned how to fight those black bug things, so…"
"We'll be leaving now," Riku translated, swinging himself into the gummi ship Cid had so helpfully 'provided'.
With a last glance at the strange pair, Sora followed him. Yeah, Riku was right to have it be just the two of them (just like it had always been), because they were adventuring, and who needed chaperones?
They'd explored so many new worlds (and Sora being Sora, made lots of new friends- and Riku being Riku, also made plenty of enemies). Now they were at the supposed end of their journey, and it certainly did have that sort of final world vibe to it, all dark and gloomy and absolutely teeming with Heartless. With a swipe of his Keyblade, Sora cleared a place for them to stand.
"So," he remarked, "there's a door. And an awful lot of Heartless around that door. And since we've been wandering around locking doors, and are apparently s'posed to save the worlds… wanna see if we can shut it?"
Riku shrugged, and lashed out at a particularly persistent Soldier. "Not like we've got anything else better to do here," he decided, and the two of them wandered over to the giant Door in no big hurry (it wasn't like they'd have anything else to do after this saving the worlds gig was over, after all, so why not make it last?).
(The Door required them to split up, but so what? They both controlled the Darkness, could tear the fabric of reality open at their will, and it was only a matter of seconds before they were together again).
"Don't you think we're missing something?" Marluxia murmured one day, as he looked over the limited profile they had of the Keybearers. "Some way to… control them?" (Briefly, a picture of a fragile blonde girl flashed through his mind, but he shook his head to dismiss the illusion).
"Why would we need to control them?" Larxene snorted. "They're already doing their jobs. Just have the old man go and knock 'em out for a bit, see if we can… I dunno, clone them or something. Then teach those clones to kill the other idiots. Oh, and collect Hearts, though Kingdom Hearts is almost complete. Least, I think it is, I never really pay attention in meetings." She shrugged and turned away, becoming disinterested with the whole business.
The Dusks swarmed around them, hissing and clawing and biting and acting just like the grunt-level Heartless did, only there were so many more of them and they were so much faster and they could use the Doors that had helped the pair for so long. They were being overwhelmed by sheer numbers, because even two Keyblades couldn't hold off thousands of these nimble silver acrobats for long.
Although surely someone would appear to save them? That was what always happened when things got this bad. Always one of Sora's friends would appear to save them, but… not now, it seemed, even though he was certain there was supposed to be (maybe a redhaired pyrokinetic he'd never met… no, that was just silly, there was no such man here).
And he couldn't see Riku anymore. Maybe his best friend was already dead, maybe not, but he couldn't do anything about it now. He was feeling strangely sleepy, for some reason, so terribly sleepy. Why was that? He looked down, the slight movement draining all his remaining energy, and spotted the gashes that trailed all the way down his body. Oh… maybe those had something to do with… with it… Hmm. There was a sort of shimmering now, and he heard Riku's voice calling for him. He'd go to it, of course. Then… everything… would be okay?
From a nearby pillar of ice, Vexen laughed harshly, pointing out the two bloody bodies to his newest experiments. "Those were the two I based you off of," he informed them, "but see if you can do better."
The Riku who stood by him grinned. "Of course we will."
"Yeah," the Sora agreed, "we will."