"She invented a musical instrument."

"Wait, really? That's amazing - do you have one around - do you have the next four hundred years of music around, actually -"

"I could make one but getting her to show you is probably a good icebreaker. Same with the last four hundred years of music."

"Okay." He takes the rolled up paper and heads outside. The door closes.

He giggles.

"If you were ever wrong you'd be really annoying, you know."

"Oh, I know."

He finds a nice spot by the lake.

He completes the dots.

There is a pause.

...it is possible that Timothy was playing a joke.

He briefly indulges annoyance with Timothy for putting this much effort into a joke too high-content to be very comedically satisfying.

But, no, if Timothy decided to try to convince him that you could summon demons from 2179, Timothy had a reason for that, and most reasons Timothy might want to try to convince him of this are just as implausible as it being possible to summon demons from 2179.

He sighs. 

He investigates the piece of paper.

It asserts that he is summoning the demon Amriac under the following limitations on her behavior and then there's several paragraphs of futuristic legalese wrapped around the circle.

Then there's a demon.

"I'm just having all the luck lately," she says, "hello, what can I do for you?"

"What the fuck, Timothy," he says aloud. "Uh, hi. Are you in fact a demon from 2179?"

"I'm Amriac. It says in the circle. Timothy was the last person in a silly outfit to summon me. Of course I'm a demon - were you expecting somebody else? Can you read? - but don't let's quiz me on Earth calendars."

"I was kind of expecting nothing to happen, actually. Timothy is my brother. He sent me a note this evening that was like 'hey come meet me on the fifth floor in that hallway that branches round the Astronomy tower and looks out on the Quidditch pitch' and then I went there and he was like 'I just dismantled Azkaban and sent everyone to the Moon and I want you to summon a demon' and he used to be the sensible member of the family. If it falls to me I'm going to be really bored. Nice to meet you. I'm Michael."

"The what pitch? Dismantled the who? Why'd he want you to summon me?"

"Quidditch pitch - are you a Muggle demon? I have absolutely no idea why he wanted me to summon you but apparently you invented a musical instrument and I would very much like to hear it, and also just generally the last four hundred years of musical history, Timothy wouldn't know how to fake that so it rules out this being a convoluted prank of his."

"Am I a what demon?" she asks, sounding as though she is considering being offended.

"Muggle. As in, not magic?"

"Demons are all magic, kiddo."

" - Quidditch is a game played on broomsticks, with animated magic balls that try to knock the players off their broomsticks while they use other balls to try to score. I am kind of surprised they don't play it in Hell, it's super fun."

"...broomsticks? Magic balls?"

"...yeah? They're called Bludgers, they're iron and like this big and they've just got a really simple homing enchantment on them so they'll fuck up whoever's closest to them but I think these days they also layer on a bunch of anti-cheating charms. Are you not allowed to have fun in Hell."

"The fuck have you been smoking?"

"This is one hundred percent my brother's fault and I should just drag him out here to close the inferential disconnect, whatever it is, but I am sure he is quietly giggling and waiting for me to do that so I'd prefer to not, if we can think of another way around it. Is the problem here that you don't believe me, would it help if I demonstrated, or is the problem something else..."

"I have one hundred percent no idea what you are talking about. Last time Parlor LARP summoned me he wanted some Elf's complete works and some old romance novels and now you're summoning me and you maybe want a sphereflute but you're talking like a crazy person and anyway you couldn't play a sphereflute."