Theo's just bitten into an apple when he feels the summons, so he doesn't stop to put it down before accepting. He can get rid of it later if necessary.
Luckily, so he thinks, he gets to the summons before anyone else.
"Change things. It's quite a broad power. Makers, unsurprisingly enough, make things, though what they can make is– kinda similarly broad."
"That's awfully unspecific, though, like, I can summon things, you probably wouldn't figure out from this description that I have to go pray to the fayth to get aeons."
"Yeah, because 'summon' to me could convey a lot of things. Like summoning someone to a court appearance. Okay, more specific, I can change physical properties? I cannot change the position, I can't change something to be magically enthralling, but I can change the color or the material or the size or shape or density or– a bunch of things, of a thing."
And Kaede seems to either not notice or ignore this, as her face lights up. "Oooh! Okay, what are your limitations, what can you change into what, how fast, why didn't you change the fiend into something, how much functional knowledge must you have?"
"Limitations vary, mainly it's a 'how much can you do over time' thing. Can change lots of things into lots of things, or I can change the individual properties. The fiend was immune, probably 'cause it was magic or something – I repeat, what the hell? Functional knowledge – it's mainly visualization, I need to be able to visualize it. I think that's what you're asking?"
"So you'd need to know the internal details of, say, a spherecorder, to change something into it? Is there a volume limit? A mass limit? How distant can you be from stuff to change it? Can you change biological stuff? What counts as magic?"
"Yeah, I can't just go 'I want a spherecorder', especially since I have no idea what one looks like except presumably spherical. Volume and mass limit is, uh. No, not really, but I don't do it all at once, it's a gradual thing if it's a large object? So, volume and mass over time, yeah, but not as a 'you cannot change a thing this large' limit, and distance is, uh, quite far, not ridiculously?" Pause. He moves a bit closer to make it easier to speak.
"Biology, yes, same limits as tech though. And I have not extensively tested the magic thing. I can't make anything magic, but you know, that could just be a failure of my imagination – pretty sure it's not, it's known that Changers can't change magical things – and I can't change other daeva much without permission, but like, that comes down to properties-of-daeva more than we-are-magical, I think. Not sure if there's, uh, actually any difference there though."
"...no, spherecorders aren't spherical, how would you even put the sphere inside it...? Anyway, what are properties-of-daeva?"
"Spherecorders are – right, the recorders that put stuff onto the sphere. Well, I dunno, could just be that you mysteriously pull stuff out of it and shove it into some other sphere, not an expert on anything sphere-related." Pause. "Properties-of-daeva vary. Include a nice, handy protection-against-lots-of-things thing."
"That I have difficulty dying and it's fortunate I'm not so inclined."
"How do you have difficulty dying? What happens if I try to, say, summon Valefor again and make her cut you in half?"
Theo looks at Tidus then continues, "I've never tested it against a– fayth? Or whatever."
"Valefor's an aeon. Her fayth is also called Valefor but that's because I'm not very creative with names. But anyway, what if Tidus tries to cut you in half with his huge sword? Pun intended."
"… Then so long as it's not magical I will not in fact be killed? And I wouldn't think I'd be killed even if it were magical, but again, haven't tested it."