i would LOVE a post on that. i have been thinking extensively about pitch romance and how deeply, cruelly toxic it is and how quadrants are in general. a lot of stuff is based in karkat's pov on it (and karkat is like. sooo biased love the guy to death but he is SO BIASED!!!) but sometimes it's in the narration and the existence of auspisticism & the fact that quadrants potentially existed on beforus trips me up as well...
this is a great question! and I suppose “the beginning” is probably the best place to start for a post about this, after all.
it’s important to be aware that when we think of Beforus as a planet that is “good”, this is not necessarily because it is wholly good by our own standards or even by the author’s standards, but because it is good within Homestuck’s philosophy, that the “good” is that which is “true” or “real”, rather than what is “true” necessarily being good. to put this in another way - which I’ve only just recently begun to fully understand myself - Beforus being free of Lord English’s corruption doesn’t mean it’s free of problems, just that it’s problems are “real” problems, as opposed to fictional problems; they’re reflective of problems we have on Earth.
pivotally, Beforus still has systems of gendered oppression, and in that sense it’s clear how the intrinsically gendered violence of Alternia’s quadrants would find their own place in Beforan society. it’s just that in this context, these dynamics arise as part of complex sociological phenomena over thousands of years and aren’t put in place solely for a specific purpose by an omnipotent time god, and as such won’t necessarily manifest themselves in the exact same ways, or necessarily be “as bad”. as with so many things in Homestuck, it’s the idea at the core of the concept that’s most important; kismesissitude and matespritship on Beforus should be recognisably the same idea as the quadrants on Alternia, just as they are recognisably the same “quadrants” practised by cherubs and humans, despite all of these arising from vastly different and largely disconnected cultural contexts.
the tendency for the same ideas to reliably bubble up to the surface again and again in different contexts is a central law of Homestuck’s metaphysics: in the words of the reliable Doc Scratch, “there is essentially nothing new in paradox space.” and it’s relevant that Scratch is the one to relate this truism, because therein lies a crucial different in connotation between “storyteller” and “narrator”; it is not a narrator’s job to invent new ideas, but rather to spin their own interpretation of what has already happened. this is why Scratch’s ancestor stories are “troll fanfction”; he’s writing an AU of characters who already lived on Beforus. we can only assume that, in the same vein, in “creating” Alternia’s quadrants Scratch merely took those parts of Beforus that were convenient to his vision and amplified them to be all-important. (alchemy, as described by 9th century author Jabir ibn Hayyan, was the transmutation of one material into another by manipulating qualities that already existed within all matter, pushing some into the background and pulling others into the fore.)
it’s easy to think of auspisticism, meanwhile, as unique among the quadrants in that it superficially seems to provide a service that is beneficial to all involved, and certainly towards Act 6 a lot of the children seem very interested in interpreting it this way. but in the narrative context in which it’s introduced to us, I think it’s clearly much more about control. as far as the ashen quadrant is concerned, what happens to the participants themselves is inconsequential; a successful ashen quadrant merely upholds the social idea of monogamy by stemming “widespread black infidelity.” which is on its own a patently absurd idea: fidelity enforced by the race who practice punishable-by-death polygamy in order to mix all of their genes together in a single pool?! yes, it makes sense within the context of a nonsensically complicated alien reproductive process, but the nonsensical complicatedness of it all is entirely the point; the quadrants are designed to intersect in ways that not even the trolls themselves could ever fully understand. just as it’s often impossible for a troll to distinguish between feelings that are platonic, pale or red, when Eridan attempts to “spark a rivalry wit)( [Sollux] to get [Feferi] to auspisticize […] and pull us out of our quadrant” it’s “t)(e oldest and lamest trick in t)(e book” precisely because it’s the quadrant working exactly as intended! all of the quadrants serve to make relationships messier under the guise of making them more structured because messy relationships make for a great story, which is Alternia’s fundamental purpose.
I think the Karkat point is worthy of another post deconstructing all the quadrants more broadly, because a lot of different things have been said about it already and it’s worth getting into, but straightforwardly I think it must be understood that Karkat and “the narration” have fundamentally the same bias; the narrative wants us to take Alternia seriously because Alternia as a machine is a construction of the narrative for the purposes of the narrative, and Karkat wants us to take Alternia seriously because he’s a massive stooge who has made his whole life’s purpose out of buying into that narrative.