The topic at hand was whether the couple-sex-mix here would turn out to have a surprisingly reasonable explanation.

Thellim can try to observe this on Wikipedia.

Before she does that, she is supposed to try and solve the puzzle herself; so that, if there is a surprising answer, Thellim can notice herself having been wrong, and ask about how she went wrong.

So.  If it's not just the world being painted in sloppily, or in a pattern that Thellim doesn't understand - then how could this result be an evolutionary equilibrium?  Or more generally, what would Thellim guess had happened here, if she'd been told it was the result of history happening?

The first obvious guess was mages enabling homosexual couples to reproduce.  It's a very elegant and clear-in-retrospect guess which would have instantly explained how sexual attraction could have come uncoupled from the previous sexual polarities, to the point where Thellim is ashamed she took as long to consider that hypothesis as she did.  But it was a very good hypothesis before Isabella shot it down.

Thellim had even got as far as deducing that, with sexual reproduction uncoupled from the original binary polarity, a new binary polarity would probably start to emerge for the same reason it originally emerged in sexual organisms; hypothesized, but not known, to reflect a divergence of sexual strategies between "fertilize all the other organisms" and "actually raise the children".  That would be the 'dom' and 'sub' part, or so Thellim had been guessing; and once 'doms' and 'subs' had started pairing off, the set of all 'doms' and the set of all 'subs' making equal contributions to the next generation would have stabilized their relative population frequencies at 1:1, for the same reason that males and females were thus stabilized.  Or to be more precise, parental investment would have stabilized at 1:1, so if raising a 'dom' takes twice as many parental resources as raising a 'sub', there should be half as many 'doms' as 'subs'.

The part Isabella mentioned earlier about 'doms' assuming more control and 'subs' having less control in relationships, on this view, would represent a new iteration of the not-entirely-pleasant strategy-divergence between "insert your genetic material into other organisms" and "accept that genetic material and raise the resulting offspring" that gave rise to men and women.  Even with the specific events of prehistory screened off, dath ilan doesn't hide that general truth of the past.  The consequence of that evolutionary logic, as executing adaptations in men and women, is too obvious to need any historical records; it's immediately visible to anybody who knows evolutionary biology and has read a few romance novels.  The untrained male has an instinct to seize and guard a woman's reproductive capacity, instinctively using violence to stop her from interacting with other men at the same time that he instinctively displays other forms of commitment to try to earn her acquiescence.  The untrained female has adaptations that assume an environment in which men will try to pressure her into more sex than is optimal for her own reproductive fitness, so her adaptations push her to instinctively resist that pressure while also instinctively trying to increase the number and quality of men who'll be interested in her.  There is a long-running dichotomy-tradeoff-argument in dath ilan between the position that this is just stupid, and somewhat evil, and was structurally evil back when some of the first sexually recombinant organisms started to specialize in injecting their genes into other organisms; and that current humans should opt out entirely from the more conflicty and combative ways that sex evolved to work, starting with using mental discipline to counteract those tendencies and eventually trying to select them out of humanity's descendants.  Versus the position that it's (1) not that bad, (2) actually quite fun in saner versions, and (3) now baked into humanity's core utility function as a top-level value that is not up for debate from merely instrumental considerations or how it originated a billion years earlier.  Almost nobody completely believes in either implausibly-oversimplified-policy-stance extreme, of course, but people differ in where they place themselves on that spectrum of opinion.

Thellim had gotten as far as reasoning through all that, and wondering whether the new 'dom' versus 'sub' sexual polarity had ended up better or worse from the standpoint of "how awful would it look to a generic nice alien that reproduced asexually" or, possibly, to Thellim herself.

Except that apparently mage-assisted reproduction is not what's going on.

It was a very pretty hypothesis, but it is, apparently, not what's going on.

So Thellim needs to properly let this beautiful hypothesis die, mourn it, and then start over.

Well, it's a bit of a premature-observation-cheat.  But Isabella did mention that Brian and Jackson could make arrangements with a female-female couple to get kids all around.  In principle, this ends with everybody having the same number of offspring and replicated genes as in two male-female couples.  Arguendo, why couldn't that lead to evolutionary equilibria that were just as stable?

Counter-arguendo (Thellim replies to herself):  Assuming both Brian and Jackson cooperate to raise both of Brian and Jackson's respective children, and the two women do the same with their two children - there'd be a lot of guardian-investment in children not genetically related to the raiser.  Over evolutionary time, you'd get guardians showing favor to their related children over their unrelated children, and maybe slipping some help to their offspring being raised elsewhere.  Which seems like it would degenerate back into heterosexual pairbonding.

For that matter, wouldn't some female-female couples go looking for unusually cheerful and healthy geniuses to inseminate them?  And wouldn't that produce dramatically greater reproductive variance for males than females, which would come with its own set of problematic evolutionary trends over time?  Or would that act of optimizing their children count as a forbidden-to-think-about concern over genetic inheritance because people in Isabella's world start murdering people as soon as they think about that, not that Thellim is worried about that or anything, it's not like anybody here thinks that could possibly be anomalous somehow, or in any ways related to this being the kind of universe that has an impossibly bizarre lunar eclipse setup and terrible airplane food that people don't notice as strange -

She's getting off-track again.  She's supposed to be conditioning right now on the assumption that this universe does have a consistent historical logic.

Thellim can't think of any arrangements for non-magical homosexual reproduction which would be evolutionarily stable over the long term, faced with competition from ongoing heterosexual reproduction.  This could just be because there's a set of adaptations for stably trading kids that Thellim has failed to envision.  But the more likely hypothesis - again going off premature-observation-cheating from Isabella mentioning relatively recent changes to sexual norms - is that the current situation is not in near-equilibrium evolutionarily.  Give it a few centuries, and heterosexuality will become more common; the remaining male-male couples will be frantically competing to become one of the couples that has a thousand children apiece with the female-female couples; and everybody will be consciously desperate to have children.

Continuing that reasoning further:  If 'dom' and 'sub' polarity isn't the effect of bipolar sexuality being destabilized by magical reproduction, the obvious next thought is that 'dom' and 'sub' are the causes of that destabilized bipolar sexuality.

Supposedly, Isabella's Earth doesn't put any care at all into preventing economically-adversarially-optimized superstimuli from being developed and released to the Network - has no concept of infohazards in general, apparently.  And to a first approximation, Earth has nobody in charge of its globally important features, which is why the interdimensional alien visitor got picked up by one helpful psion and taken to a small apartment.  So some porn-making corporation could have developed superstimuli versions of sexual polarity, icecreamizing male to 'dom' and female to 'sub' in ways that bound more tightly to sexual receptors than the original sexes; and then that meme spread like a detonating supernova through their whole civilization and entirely displaced masculinity/feminity.  Without there being even the theoretical possibility of anybody who could stop to question whether that was a good or bad thing.  And the new situation isn't evolutionarily stable, but Isabella's people can't let themselves think about that or where the new setup will trend or eventually stabilize, because then they'll go insane and start stabbing each other with kitchen knives.

So that - feels like Thellim's current hypothesis, more or less?  Her guess in advance of observation?  It's not a very polished hypothesis, but Thellim doubts she'll come up with a much better one for further thinking.  The point here isn't to be correct, so much as to notice what she learned after finding out the correct answer - to notice which parts of Thellim's wrong background reasoning helped produce her no-doubt-wrong conclusion.

Of course, that's assuming the Network even contains an answer.  Most of Thellim's guessing-probability is on "There literally isn't a historical reason, and people in this layer of reality are not noticing that their airport seat designs and sexual emotions aren't plausible equilibria of historical developments."

And that's quite enough trying to guess the answer in advance.  Thellim has been good, she has been very good, she has been super scientifically virtuous about being explicitly wrong in advance, instead of pretending afterwards that she was "mostly on the right track".

Now let's start Wikipedia-ing... what keyword, exactly?  "Why isn't everybody heterosexual?"  That sounds like a Network query rather than an encyclopedia article title, but maybe the Network query will tell Thellim what keywords she should even be checking in Wikipedia.

First google result:  "The invention of 'heterosexuality' - BBC Future".  It mostly seems to be arguing that 'heterosexuality' is a stupid concept and shouldn't even get a word in the language or be taught to children, although of course the article doesn't phrase it that way because sanity forbid that anybody try to coordinate around children learning optimized subject matter or that anybody try to design a language to facilitate clear thinking.

Okay, let's try: evolutionary biology of doms and subs.

Oh.  Apparently 'dom' and 'sub' are actually short for "dominant" and "submissive".

Is this actually as bad as it sounds from the words?  Maybe she should just read the science paper she found before panicking.

This is very rapidly heading in a direction that is very not good.

The science paper seems to be talking about ways that 'dom' and 'sub' key into evolutionarily older adaptations and it's confirming in passing that the shift in sexuality is recent, though it frames it as an insight into something that was always true, but there's - there's hints of - things worse than dominants giving orders and submissives taking them - of course this world would somehow manage to invent something worse than masculinity and feminity to replace it -

Stop.  Deep breaths.  She's not quite distressed enough to fall back on solid-core reasoning, but she is in literally another dimension and needs to be careful about jumping to conclusions.  All her predictions have been horrible and that's not a good sign for her models being real.  She is not necessarily the protagonist who got transported into a broken world in need of fixing through the power of clear thinking and good coordination; she may be in a cautionary tale about protagonists who think they know what needs doing when they really, really don't.  Jackson didn't look unhappy or scared of Brian.

Of course that could be because Jackson wound up with an unusually nice dominant, or because that was a good day in that household when Jackson didn't get any horrible orders - for that matter, there's some of the less fun to think about behavioral-econ experiments, the ones where the experimenters didn't push nearly as far as it looked like they could have, for ethical reasons, but which were awfully suggestive about what people might end up being happy to get by contrast with much worse deals they could have received -

Maybe Jackson seemed happy because he was getting fed that day.

Maybe she's making things up that completely fail to be true.

She needs to figure out - a Google query, a Wikipedia keyword - and screw making predictions in advance - but her System 1 seems to be frantically scrambling even as her System 2 yells at it to calm down and she can't figure out what to query to figure out which kind of protagonist she is, whether this is a horror-world or if she's just failing to understand a coherent set of customs that make moral sense once they're explained, Isabella thought that "submissives" liked taking orders, but of course Isabella is a dom and nobody in this world is going to have the tiniest training against self-serving beliefs because you have to think about children's education to do that -

What happens when a submissive decides he doesn't want to submit - when a submissive refuses a dominant's order?  Maybe there's some more incisive question that would separate the ethical possibilities, but right now Thellim's System 1 is scrambling and she just types in the first Network query she can think of:

What happens to subs who are disobedient?

There's - there's a wall of text excerpted from links and awful words jump out like punishment and more awful phrases like fun punishments for your sub but maybe it's just extra homework she has to not panic until she's sure, and unknown terms like "safeword" that don't translate but sound vaguely reassuring to whatever probable-dom put this language in her head, Thellim's eyes scan over fragmented sentences she doesn't understand but that definitely aren't reassuring her, and then stops at a link that promises to show a video of what happens to disobedient subs and video sounds easier to understand than the excerpts of sentences Google is showing her so Thellim clicks through.

no no no NO NO NO she doesn't want to be here she doesn't want to be in this horrorworld she doesn't want that to happen to her no no what if Isabella thinks Thellim is a sub is the person in this video rescuable no they have to be dead by now nobody could withstand that kind of punishment for long without dying

Core reasoning patterns fallback.

The video is hurting her.  It needs to be turned off.

It is now permanently seared into her memory.

She needs to think about other things anyways.

One of the primary core reasoning patterns says not to kill yourself.  This potentially needs to be adapted to circumstances.  What she saw in that video looked a lot worse than death and probably ended in death anyways.  Killing herself is a potentially reasonable strategy if her chances of ending up like that otherwise look high enough.

Alternatively, she could try to stay here and fix this broken world, and risk ending up like that herself.

That should have been a very fast decision, shouldn't it?  The correct course of action is that she's supposed to fix this world, right?  Thellim is one person.  The number of disobedient submissives being punished right now is much larger than that.  Why is this decision hard?

It's sad.  Shameful.  Thellim thought she was more of a, protagonist, than this.

Could she be, misinterpreting, somehow?  Or missing background information?  Is there an argument she's missing for why that was, in fact, a perfectly reasonable and ethical thing to do to somebody?

It's that last thought, in the end, that manages to light a tiny spark of deep, bone-searing anger inside her.

Deep.  Fucking.  Breaths.

No.  No, there CANNOT be some unknown fact or unseen line of inference which justifies this.  This is a not a novel whose elaborate lesson will turn out to be about the importance of perspective-taking and appreciating that other people may have unseen knowledge and arguments that you failed to imagine and which paints them in a much better light than you first thought.  If this were a novel, which nobody would ever buy, it would be a novel whose lesson was that there are SOME THINGS WHERE YOU DON'T HAVE TO WONDER IF THERE'S A JUSTIFICATION FOR THEM AND YOU CAN AND SHOULD BECOME UPSET WITHOUT FURTHER HESITATION.

She has just seen a woman restrained so that she can't get away, can't even move, as one man - who had a - that he was using on her unprotected - while another man was violating her - you do not get to reveal hidden arguments why that is acceptable to do to anyone under any circumstances ever.  Nobody, not even somebody who'd wantonly murdered a city, not even somebody who'd done that to someone else.  It would be a case of something where the author shouldn't even put it into the story's worldbuilding, because even as an example of evil it would traumatize the readers and numb their moral sensibilities to saner sins, and if there was the slightest hint that the author thought it could even possibly maybe be okay, if it looked like the sequel was being set up to reveal a clever argument for why this was a perfectly okay thing to have happen in society, the correct coordinated response would be to ban the book.  You do not get to put that into your fun thought experiment for what a different possible society could maybe think was okay.

But she doesn't - doesn't want that - to happen to her.  She really doesn't want that.  To die.  Like that.  Flinging herself off an apartment balcony before it can happen seems like a perfectly reasonable strategic response.

It has not been shown that this outcome is a high probability.

By the time it looks like a high probability it may be too late to commit suicide.