I'm not wild about a lot of elements of 'postcanon', but the friendship between Karkat and Calliope is great. I've always, always thought they would make amazing friends, like Karkat is sort of the brother Calliope never had, all of the like, limeblood/mutantblood stuff, the 69 cuffs, there's SOMETHING there!! So as much as I hate what they've done to my lesbians, HS:BC absolutely nailed it in terms of showing Calliope and Karkat just. Naturally understanding each other on some level.