"That definitely sounds like a safe assumption I should advertise having made!"

Sigh. "So imagine you're a demon who is summoned to an Arda and asked to make this outgoing army a fleet of starships, what do you do?"

"...try to see if they're doing something useful or just marauding randos with poor logistics?"

"Yeah. So Cam agrees to make and administer a secret refugee planet, and to do more looking into their reasons for going to war. They recommend him all their published materials about the Enemy, which would be hard to have designed in a way that let you deceive a demon - but he doesn't want to rule it out, because this world has a lot of technology that his native world doesn't. In particular, Elves in this world don't have immortal souls, like the kind of Elves you're used to - instead, they write the contents of their brains to little metal chips in their heads, and Mandos has backup copies of the chips from which he can resurrect them. So he makes the refugee planet, relocates some refugees, and lands with them on Endorë to try to determine if they're telling the truth about the war.

He discovers that the Enemy is in fact horrible. One of his favorite hobbies is killing people in ways that leave their chips intact, and then - running them - off the chips, very fast, a thousand or ten thousand years in a year of real time, and he has millions of prisoners. And he offers Cam a deal. The deal is that Cam destroys Valinor - which is easy to do with demon powers - and kills everyone on it including the Valar, and in exchange the Enemy will let Cam evacuate Endorë."

"To, what, be chased forever?"

"Would have been very hard to find them, space is big. Cam turns him down. Then the me is among a hundred million people who get captured when the Enemy deploys a - disease - that kills everyone silently in their sleep so he can come by and get the chips from them. And the Findekáno figures out how to resurrect people without Mandos helping. 

And Cam figures it might be worth it to take Melkor up on the deal. He tells him he'll do it in exchange for an oath - he found a way to verify - never to hurt anyone ever again, or let anyone under his command do that, to stop all the torture and all the war. Melkor agrees."

"Mm-hm."

"So Cam does it. And then he makes them a new planet and starts resurrecting everyone he can, fifty-four million of them, and when he's halfway through it he runs into a Milliways door."

"What a delightful stroke of luck."

"Luck would've been getting it six months sooner."

Nod.

"Anyway. The door had also recently opened on another planet full of humans, some small fraction of which have the ability to perform magic. That world, Hazel,'s tech level is comparable to yours but without servantmaking, and the magic-users government is pretty horrible, the me and the you were planning to take over the world because it needed it. So Timothy meets Cam, they exchange notes, Cam can help Timothy's world a lot with technology and also he teaches him to summon and they learn in an accident that summoners from anywhere still daevafy, and he starts planning a rollout of summoning in his world to stop all its humans from dying. This is complicated by the fact that summoning is very dangerous if you don't know what you're doing and Hazel's population is mostly illiterate."

"My world's population is not mostly illiterate."

"Yeah, you seem to have gotten a lot of mileage off servantmaking in terms of quality of life advances that human populations mostly don't achieve until they industrialize."

"Servants don't teach kids to read, creche minders do."

"Yes but you are far enough above subsistence labor that they can afford to do that."

"Seems inefficient to teach kids anything if they can't read. Whatever."

"I think they mostly farm and serve as servants to richer humans and raise their accidental children and that's about it?"

"Who, the Hazel people?"

"Yes. My world doesn't have any humans."

"Okay."

"Anyway. They're working on this when Mingling - the me who is seven - walks in. And frightens Cam pretty badly, because chip Elves can't osanwë at him and the little me read his mind when he was thinking about the destroyed planet and then both of them freaked out quite badly."

"Blatant plagiarism, minus ten points."

"That's in a hallucination?"

"It's in when I landed in Valinor."