He doesn't swim naked, so he takes the summon anyway.
In a language that shares no discernible roots with any Cam has heard before, the short tailed boy exclaims, "Crash the sun!"
Cam flares his wings when the surface tilts, but it's no good, he's slippery when wet, he topples over anyway and makes an undignified noise. ...He can make an undignified noise. They're letting him talk. These people have tails. What.
One of the others, too far away to help, moves as though to attempt a catch but gives up a moment later when the demon hits the floor.
"What did you do?" he asks his presumably-brother.
"I didn't do anything!" he says. "I don't know where this guy came from!"
Cam sits up and shakes water from his wings. "You weren't trying to summon a demon?" he asks. He renders it as 'maker'. If they have a word for demon he didn't get it in his vocabulary dump. Outside chance they do have one; but the engravings aren't actually in a language he got from the summoner.
"I was trying to learn artificing. I've never heard of winged strangers appearing on top of anyone's fire shield prototype," says the probable summoner.
"No one's made a fire shield this big before," says the third boy. "But even so."
"Yeah, this looks like an accident. But it's a very confusing accident. Especially if you did not previously summon another demon or an angel" ("changer") "to outfit you with the cunning tails." He lashes his own tail.
"...We were born with these." The speaker gives his own tail a slight sideways flick.
"We're Aluvai," the summoner explains, sounding like he can't imagine anyone needing to have Aluvai explained to them.
"And, er... what are you?" asks tail number two. "Because I'm less and less convinced that 'winged stranger' is the sum of it."
"If you've got a word for me I didn't get it. 'Demon' in my native language, 'apsel' in a favorite later acquisition, I called myself a 'maker' which is basically what 'apsel' means. Where I'm from people are not born with tails."
"In Aluvanna people are born with tails regularly and unremarkably," says tail number two. "Although never ones quite like yours. And there aren't common categories of people that I would think to call 'maker' and 'changer' and expect anyone to know what I meant. And people do not customarily appear out of thin air atop one's fire shield prototypes."
"Well, you probably shouldn't re-use this fire shield prototype, because it appears that it summons makers in a complete absence of safety precautions! Generally inadvisable."
"...What safety precautions are normally advisable when summoning a maker?" he inquires.
"It's smart to have something laid down to prevent us from using our phenomenal cosmic power to hurt anyone, unless that's what you wanted the maker for in the first place anyhow, and also typical not to let us talk but that part's not necessary."
"How lucky for everyone involved that you do not wish to use your phenomenal cosmic power to hurt anyone," says tail number two with perfect equanimity. "What sort of phenomenal cosmic power is it, exactly?"
"I bet you can guess." Cam tilts his head back, creates a marshmallow, and catches it in his mouth. Chew chew.
"Crash the sun," breathes the summoner. "Did I just save the world?"
A brilliant white glow collects in the air around him, reaching up and down to join floor to ceiling in a solid column of light. When the glare clears mere moments later, he has acquired a pair of wings, raven-black with silver-edged feathers, mantled in startlement. They somehow interact unproblematically with the shirt he was wearing.
Cam opens his mouth slowly, points at the summoner, and says, "I did not do that."
He stretches the wings, folds them, and... they vanish. Cam sure didn't do that.
"I did not appear wings on you? Normally if I were in a room with a bunch of people and somebody spontaneously acquired wings I would be the obvious person to blame. Where did they go. What is going on."
"They're my wings," he says, as though the relevant implications of this statement are too obvious to make explicit. "...They're my wings. Crash the fucking sun, I just got my wings. Ha!" He laughs with amazement.