It is very solid!

And there's a man standing there, now, with his arms folded and his back to Theo. He wasn't there a second ago, but he didn't really appear. It's more like he'd always been there, but Theo hadn't noticed. The man is shirtless and barefoot, and his stance fails to hide the armour covering his left arm.

"… Hi there."

The man turns around to face Theo, revealing a muscled chest tattooed with a symbol that looks exactly like one Theo's seen on Tidus' shorts.

"Who're you?" the man asks, looking confused.

He does not remark on Theo's nudity.

"Theo," he responds. "Who are you?"

He makes no comment on the other guy's (half-)nudity, either!

He raises a hand to the back of his head and scratches it. "Sin, I guess."

"… And why are you Sin?"

He shrugs. "How it works. Someone has to be."

"Couldn't there just be nobody who is Sin?"

If he tries to turn a piece of the man's clothing blue, does anything happen? What about a piece of his skin, change the color briefly.

Nothing happens. Man's as magical as the rest of the place.

"Ain't that a thought. If you figure out a way to do it, be sure n' tell me. I had a friend once who... Nah."

"– I assume you don't want to be Sin, then?"

"Farplane, no. Who'd want something like that?"

"I didn't realize there was anyone to want or not want it."

"Yeah, guess no one does. I didn't, before. Well."

"Well?"

"Before I became Sin."

"I am missing lots and lots of details on the process here? How did you become Sin, why are you Sin and yet not able to stop it…?"

"I don't really know what happened. I thought we were gonna kill Sin. Then I died. Then I fought Sin. Then I was Sin."

"… I don't understand what it means to 'be Sin'. You don't look particularly Sin-like, nor do you seem like you actively want to hurt people?"

"Well, not right now. But sometimes I do, n' that's part of it. Sometimes I get enough control, and I can steer a little. Away from bigger places, with more people, when I can."

"Oh, you're under occasional mind-control to go kill people. Wonderful." Sigh. "Are you trapped on that thing?"

"Yeah."

"Do you think I might be able to get you off it?"

"Are you an aeon?"

"No? At least not in the regular way." He turns some of the skin on his hand blue, then holds up his blade again. "Made this, though."

"Don't think you can help, then."