Aaa I’m not great with historical AUs and can’t think of a humanstuck one, so let’s go with… my extensive headcanons on Alternian history…
It’s the very early days of the Alternian empire, with the Condesce having conquered the seas and now just starting to turn her attention to the general landdweller population. Karkat and Gamzee are young trolls living in a coastal but still independent hive-colony.
In their community, trolls of atypical color are considered to be seers, or sometimes even omens in and of themselves - an unusual belief, but not unheard of at this point in history, and part of the reason for the Condesce’s strict policies on caste purism. As such, although Karkat doesn’t have a lusus (as his was, in canon, provided by followers of the Signless) he was cared for and has spent most of his life in the hive-colony’s breeding-cavern-cum-temple-complex, becoming increasingly dissatisfied with life because he does not, in fact, have any precognitive powers, mutant-related or not. By the time he’s six sweeps, he takes to sneaking out into the city when he’s bored, even if most of it is incredibly dangerous for a troll his age.
Meanwhile, Gamzee has been displaced from his wrigglerhood hive by encroaching imperial forces; he’s pretty sure his lusus is dead, his hive is too dangerous to stay in, but he doesn’t have a lot in the way of connections in the city and six is really too young to even try to integrate into adult society. By the time he first encounters Karkat, he’s living on the streets, his existing tendency toward substance abuse strongly exacerbated by the stresses of his current situation.
The pampered, disaffected mutant and the unusually highblooded street rat strike up an unlikely moirallegiance, lessons are learned about tHe oNlY ThInG YoU GoTtA Be aN OmEn oF Is yOuR OwN FuCkInG SeLf and SOPOR DOES NOT, IN FACT, MAKE YOU MORE EMPLOYABLE, ALSO WHEN WAS THE LAST TIME YOU WASHED YOUR HAIR, and… we’re probably left with an impending sense of doom because let’s face it neither of these idiots is going to last long when the Condesce takes over.