He's sparring with Even the first time it happens. They both prefer more intellectual pursuits, and both their minds are drifting elsewhere in spite of the General's best efforts, when his practice sword meets Even's shield with an unexpected clank. Even stumbles backwards with a sort of startled squawk while Xehanort stares at the black and crimson thing in his hand. "What. Is that."
Xehanort blinks at it, makes a few experimental slashes in the air. "Some sort of summoned weapon, in— a markedly unusual form…"
"A brilliant deduction," Even says dryly. "And silly me, I was thinking it was, oh, a cooking utensil. Here, let me see."
Except the oversized key vanishes seconds after he hands it to Even, and all of Xehanort's efforts to call it back again fail miserably.
"That… was interesting," the General idly remarks to their backs, but they've both already set off at an undignified run for the labs, calling incoherent apologies over their shoulders.
After spending the next hour waving around the wooden sword and at one point a discarded popsicle stick while the others shake their heads and take notes and talk amongst themselves, Xehanort almost regrets telling Ansem what happened.
"This is going nowhere," Ienzo says finally, voicing what they're all thinking. "A phenomenon has to be replicable if you want to experiment on it, and obviously this isn't."
"Maybe his life has to be in danger," Braig says with a frown, and Xehanort edges away as unobtrusively as he can. Even protests that he certainly wasn't trying to kill Xehanort at the time, although Xehanort almost managed to bash his head in with that ridiculous thing, and that somehow devolves into a discussion between Elaeus and Dilan on how to make a key into a plausible weapon.
"Keyblade," he says when Dilan insists on calling it a mace. When they turn to look at him he shrugs. "It… sounds right?" It had fit his hand like a blade, not a bludgeon, but somehow he suspects flesh and blood were never what it was intended to cut through.
The second time he isn't thinking, because there's a shadow diving for his chest, and however pudgy and harmless the Heartless look, those claws hurt. Xehanort barely even notices that he's killed the first one, but once he realizes what the key can do he turns to deal with the rest, and there isn't time to think until all the shadows have been sliced to nothing but scraps of darkness and the brief glint of a heart.
…he probably shouldn't be feeling guilty about that.
The Heartless go back to their usual docile selves soon enough, but it's a reminder of what they're dealing with and how careful they have to be, and the others look at Xehanort with new respect. Not deference, because the friendship between them is too close for that, but there's no question now of who the leader is.
There's also no question of telling Ansem this time, because the blind fool's already proven how unwilling he is to try to understand anything that matters. And in any case it would require explaining the circumstances, and all they need now is for Ansem to stumble over their experiments again and end them permanently this time.
Xehanort's left to ponder it himself, and to come to no better conclusions than before. He wouldn't have guessed he was a warrior of any sort in his life before, because scholarship comes to him naturally as breathing, but. The keyblade feels right in some inexpressible way, and he thinks it could be the answer to everything if only he could see a little farther into the darkness and understand the slightest bit more.
The third time is no accident.
When Xehanort follows the Shadow down a spiral stair he doesn't remember and turns a corner to find the door waiting for him, there's no surprise, just a sudden certainty that this is what he's been searching for. It's only rough-hewn stone like the rest of the dungeons, no mysterious sigils or aura of destiny, but the ornate keyhole at its center tells him what needs to be done.
The key comes to his call for once, cold and heavy in his hand and wonderfully familiar. For a moment he stands there like an idiot wondering what he's supposed to do next, but the keyblade, at least, remembers.
There's a faint click, and the door melts away into darkness.
Beyond it is— something vast and beautiful made of dark and light that pulses like a living thing, and that he can't seem to tear his gaze away from. More dark than light, by far, he decides.
Come back to me, the darkness commands him in a hundred different voices, Xehanort, my lost one, and then it says another name that never quite reaches his ears. I will give back what you lost, return you to who you were.
Xehanort takes one step forward, and another. Out of the corner of his eye he can see the Shadow bending at the waist in some bizarre obeisance, whether to him or to what's beyond the door he can't guess. Dark tendrils reach out to welcome him in and—
And then the other five apprentices clatter down the stairs demanding to know what he's gotten into this time, and the door is just a door, for the moment.
"Something to be studied, naturally," he says, though turning takes more effort than he expected and he's tempted to take those last few steps into the unknown. But not yet, not now, when his theories are still falling into place and he's still not quite certain of everything.
There's a brief uncomfortable silence, and then Even brings up their discussion of whether worlds themselves can have Hearts, and how isn't this incontrovertible proof of that, and then they're all talking and Xehanort manages to laugh and join in and walk away.
I am infinitely patient, sighs the darkness behind him.