They can. They do.

They take him upstairs. "If he thinks we're - Angband - he's not gonna answer what we can do for him, do you have any guesses -"

"I have never been to Angband - and the chip one is different - and I don't have a model of why he'd do this instead of critiquing my fashion sense or something -"

Nod. "...leave him alone for long enough to see if he'll eat, like you said, and then Veritaserum can at least elicit preferences about supervision and so on - do you want to leave him the means to kill himself -"

"Yeah. I want to be kind of excruciatingly conservative about assuming he'd want it but if it's there and he goes for it I'm not gonna second-guess him."

"Okay. If he's just a normal human there're potions that're painless."

"Several of them? Who develops these things?" Room. Door.

"Assassins who expect their enemies are checking for specific things but have no way to check in full generality. Mostly. Accio -"

Cam puts a meal that will still be reasonably tasty if left there for hours and should be comprehensible crossculturally on the room's desk, and makes a label that reads in bright colors Lethal Poison [Optional] to put on the potion.

Here is the potion. "- if he'd prefer to continue to exist under the conditions 'indestructible magical being' but not otherwise -"

"If he wouldn't prefer that we can't undo it."

"I know."

"Also it'd become a problem in case of the 'murder forty people in the night' thing."

Shiver. "I hear things go badly when the daeva is smarter than the summoner but 'you with all your faculties' is smarter than 'you being catatonic for some reason'. We'd have to grab him back but we could do that."

"If he recovers enough to, like, answer yes-or-no questions, revisit it then, I think..." But he adds a note next to the lethal poison that if he can hold off on taking it and hold a conversation they have 'indestructible magical being' on offer.

"And maybe put on some music or something?"

"Yeah, good idea." Cam sets up a nice long playlist.

"And I will be wildly optimistic and suggest instructions on how to contact you as well."

"I was just going to conjure the plate periodically to see if he'd eaten, but sure." Little notebook, pen, introductory paragraph.

And they leave.

"Wonder if the Killing Curse works on Maiar and Valar."

"We were wondering this about the Imperius a while ago, weren't we?"

"Might not have the same answer, since the Imperius works on daeva and Avada Kedavra doesn't. And there are already Melkor containment solutions in place, what I want is a way to kill him. Them."

"Small you's world has one captive, maybe they'll hold him still and let you try it."

Nod. 

Sigh.

Wingput.