"Yeah, exactly, since otherwise you experience potentially fatal health problems. Might also explain your hypothesized lack of trauma reaction to all the sex stuff I was complaining about? There's a psychological phenomenon humans can get that's probably an adaptive to response to 'oh no, I have been captured by an enemy tribe' - it might make some sense from a third party perspective for this to just be game over but evolution isn't metaphorically cool with there being a game over so instead human psychology goes 'okay I'm in this tribe now that's fine I can still have a bunch of kids'.
Maybe you have a mini version of that kicking in whenever you're in debt and somebody's like 'let's solve this by having sex', since if you were like 'no' this would make you seem disagreeable, or something."

"I observe that human slaves are also broadly pretty cooperative and yet your analysis there is that we're still hurting them quite badly?"

"Yup! This psychological quirk is best construed as a trauma reaction!"

"That - doesn't feel to me like an accurate description of the thing that's going on when faeries are ordered to have sex. I don't have much in the way of non-faery examples to work from, but something doesn't fit."

"I mean, yeah, I'm just speculating."

Nodnod. "There've got to be other things, too, that by rights ought to be upsetting but that actually it's rare to be upset about? Are there humans who have trauma about needing to excrete waste?"

"Uh, maybe, but it'd be a really obscure psychological problem."

"Because it's common enough that it'd be really, really maladaptive to get all upset about it, even if in the abstract it's kind of unpleasant and even if, described to aliens, they might assume one would hate it?"

"I... guess you could draw that analogy? It does feel salient to me here that nobody is going around inserting waste into people so they have to excrete it, there's no agent involved - humans can get trauma about things that don't involve other agents but it's way rarer."

"That's interesting."

"Maybe it helps that the magic debt thing is itself conspicuously not an agent? That's conspicuous to you, I mean, you have some direct sense of it, humans don't, they just see faeries doing stuff to them."

"Maybe. With sex in particular there's that - it's one of the fastest ways to reduce debt that doesn't require exceptional levels of ability in something. The only thing that's faster is violence. So generally, telling someone you want sex is friendly in that it's... the likeliest result of considering their time valuable and not wanting to hurt them."

"That makes sense as a signaling thing, yeah."

"Though it's also rare for faeries to be traumatized by violence, if I'm understanding traumatizedness right."

"Humans get traumatized by violence pretty routinely. Also unwanted sex and violence are correlated."

"If you tell someone to have sex with you and they say no and then you hit them until they cannot object and have sex with them you have done something rude, by our standards."

"Well, I guess 'rude' is something."

"There are a lot of details that'd be relevant to how people evaluated it but - that's not a normal sort of behavior, when I say we're all breaking this rule of yours all the time I don't mean that."

"Oh good."

"Anyway unless we had a lot more mortals who wanted to cooperate with testing I doubt we'd nail down exactly the ways we're different but we do seem to be, and the debt system feels - pretty much reasonable to me. Not exactly the way I'd design it but not irrelevant the way it is to you."

"It has... obvious exploits, which I think would stop me from taking it seriously as a grounding for right behavior, even if I considered its archetypical use cases reasonable."

"It does have those. It feels to me like it's basically shaped around the right things but then you can use it to do horrible things if you're clever enough."

"I think a credible metaphysical instantiation of morality wouldn't have that, so my suspicion is that faeries are molded around the system and not that the system has anything of general interest to say about the nature of ethics. Sort of like... sugar tastes good, but in humans that means that anything in the ancestral environment they found with sugar in it was probably a good source of calories and vitamins. It doesn't mean that sugar fundamentally is tasty. Cats can't taste it at all and that doesn't make cats wrong."

"I guess I'm not sure there's a general nature of ethics any more than there's a general nature of tastiness."

"I think there's - such a thing as moral progress, and even if that doesn't imply a single coherent destination, it implies that some directions are better than others."