"Possible horror reactions include 'oh my god, you steal people's babies when you don't just outright kill them' and also 'oh my god, as soon as you have a way to do it you will cheerfully overrun the entire universe'."

Sigh. "I wonder - if we put our terraformed planets in a slightly more distant orbit, stretch the length of a year by a bit - whether that cuts down how many children people want. It might, but it also might just make it so you want one every spring, because your one-year-old isn't small enough."

"...because your one-year-old isn't small enough," repeats Cam. "Wow."

"Springs are okay when you have a kid who is almost one. By the time they're almost two you want a baby."

"This seems awfully all-consuming."

"I would kind of expect all evolved species to be like this, really."

"For humans not having birth control for much of our history does the trick. For a while after its invention some societies where it was widely available were below replacement; after that you have to make having kids easier for it to be appealing to most people."

"And even after a while of that you didn't end up strongly selected for wanting kids? Maybe traits in general are less heritable for you and that explains both the no caste system and the not strongly wanting kids."

"Traits are pretty darn heritable, but not so much that birth control being available is a perfect sieve for desperately wanting ridiculous numbers of children and not being able to solve this emotional problem by getting a dog or learning to quilt or something."

"Pets don't really do it. Living with younger siblings or nieces or nephews or grandkids mostly does it - Aitim's all 'we should wait for a politically convenient arrangement for the mothers' but he has six little brothers to spend the spring snuggling - three-parent arrangements usually work but require solving harder parent-compatibility problems..."

"Wow, your species is like actually kind of a utility monster."

"It'd be really convenient if there were a way to settle us in your universe of origin and if people born there become daeva."

"Because it's not as crowded?"

"Not as crowded, wars would be enough of a catastrophe that no one would think about it, no meaningful resources competition no matter how many of us there get to be, everyone else has a ridiculously easy way to pay demons."

"The ridiculously easy way being letting them adopt kids? The Martian power grid runs on letting fairies do that."

"Yeah. Or, honestly, even letting them hold kids, but letting them adopt would be the decent thing to do."

"Jesus," says Cam.

" - that only sort of translated, with strange results."

"Sorry. I was using it as a generic exclamation but it's got some etymology."

"Anyway, we need way more daeva and we've got a species that reproduces fast and is easy to pay, it seems like there really ought to be a way to solve one problem with the other, here."

"I suppose I could probe further into the mysteries of the magic door but you're not going to realistically march thirteen billion people through the magic door."

"If it turns out to be possible and to work the way we're hoping we'd buy this apartment building and convert it to a government facility, announce we're doing a colony planet, send like forty thousand people through, send more of them in batches later. It wouldn't put a dent in our population but it'd grow fast on the other end - without scarcity I bet people go higher than five -"

"Oh, I thought you were hoping to decomplicate meeting the neighbors."

"I am also hoping to do that but separately." Sigh. "....we could tell the neighbors we're working on genetically engineering ourselves to want fewer children, see what they make of that."

"That wouldn't be horrifying to the subjects?"