Continues to be magic and therefore unchangeable, like all the other fiends presumably?

Yep! And may in fact not be a fiend given the way its only uncovered eye goes bright and then a random fiend explodes. And another. And another. And another...

Well, that's– dramatic?

He'll. Uh. Watch it warily and wait in case anybody wants to suggest some way he can help out with something. Like getting rid of it if it does in fact turn out to be necessary to do so.

Eventually all fiends are dead, and now that there's a pause in all the eye brightening schtick it's possible to see that the giant monster's uncovered eye is bleeding, a small waterfall of blood leaking into its bandages.

And then Maester Seymour does a cutting gesture with his arm and the giant monster disappears with a ripple in the air.

"… Does anyone have any idea what the hell was with all the fiends?"

"Someone must've let them in, there's automatic weapons and a guard protecting the city, but you don't usually see that many even in the wild..."

"That's a mystery alright but can we talk about Maester Seymour's aeon? I mean, I didn't hallucinate that, right? That was the coolest thing! I wanna know where he got 'em!"

"It was kinda huge," agrees Theo.

He looks at Valefor and pats her beak. "You're pretty cool, too."

Valefor screams, then flies into the sky, disappearing in the distance.

Auron looks at Kaede, then at Kimahri, then at Theo.

"And you are?"

"Magic, not really an aeon or a fiend, got summoned– yesterday? Have the ability to change things from one material to another or, like, temperature and density and stuff?" Shrug. "Kaede summoned me."

He looks at Kaede.

"I will totally tell you all about it later, but the whole 'waltzing back into my life after ten years and demanding to know things' schtick will not fly so we can do that after you inevitably decide to come on my pilgrimage with me because of some promise you made or something."

– Ouch.

He looks at him for a long moment, then nods, looks at Tidus, and says, "You. Come."

And off he goes somewhere.

"What? Why? H—hey! Don't just leave me!"

And he runs after the quickly retreating man.

"Wait for us," he calls over his shoulder.

"… Uh. Is he usually like that, I forget how you described him."

"I think the relevant information then was that he didn't draw much attention to himself."

...red coat and giant samurai sword notwithstanding, probably.

Probably.

"So, I assume we wait then?"

"I gueeeesssss," he sighs. Then looks at Wakka. "Good game, by the way, congrats."

"Yeah," agrees Theo. "I mean, I haven't seen a whole match before or anything but it looked good."

"Oh, thanks. There was supposed to be a ceremony after, dunno what's gonna happen now."