He sighs. "It's fine." Pause. "Not the expulsion, I mean, that's not fine. But... surely if your magic can summon it can also... I don't know, return, push, send? Even if it's not just a direct reversal of calling me here."

"You can only send people from their original world," says Korulen, starting to pace.

"So is summoning and unsummoning the literal only known method of interdimensional transit?"

"...yes?"

"How is new magic invented or discovered?"

"New wizardry?"

"Right, how does new wizardry—happen?"

"Um, people develop spells? I haven't taken that class yet."

"Okay, so it's not the worst outcome, there could be a way to send me back."

"But we can't do it."

"Is there any reason you can't keep me a secret in this room, other than the obvious one of it being kinda weird and creepy to have a random dude in a young girl's room?"

"Uh, other people come into our room ever?"

"And that'd be impossible to avoid for the next few years? Hmm. I... could probably develop a spell that makes me unnoticeable but I'm not sure it'd work beyond this ward, and also I'd eventually run out of mana unless I got another source."

"And people could see the diagram."

"Could possibly make it invisible, too... or maybe cover it with a rug?"

"The rug wouldn't go through the ward."

"Hmm... can you make a ward that selectively lets stuff through, or only from the one direction, around this one, and then unmake this one?"

"No."

"Which part of that is impossible?"

"We're not going to break this ward!"

Blink. "How... were you planning to get rid of it after I was gone?"

"It'd be fine if you were gone but you're not going to be gone you're stuck."

"Oh you mean you won't break the ward, not that you can't. But like, if there was already a ward around this one that was just as good before you unmade this one what would the problem be?"

"It wouldn't. Be as good."

"Why not?"