Information Chapter:
There's probably going to be a lot of confusion over the family situations coming up pretty soon so I wanted to warn you guys here and also fill you in on them. There will also be information on the relationships and friendships here. Feel free to skip it now, but if you're ever confused later on, just pop back in and see if your question can be answered. If it can't, leave me a comment and I'll gladly answer it for you.
Egberts/Harleys/Crockers/Englishs: Jade and John are twins; their mom died just a few short months after they were born, leaving Dad to take care of them. Jane is their older sister and Jake is their cousin, though he lives nearby. The family has two grandparents alive. A grandmother on their mom's side and a grandfather on their Dad's side.
Striders/Lalondes: Bro and Mom Lalonde are known as Davis and Rita in this universe, and are married. Davis is the older brother of Dirk and Dave (Dirk's older than Dave.) Rita is the older sister of Roxy and Rose (again, Roxy is older than Rose). It's only mentioned a few times what happened to their parents because none of them like to talk about it. They're all step siblings, but treat each other as if they've been together for life. No grandparents and that's pretty much all to say on their family.
The Midnight Crew: The midnight crew adopted Karkat, Sollux, Aradia and Tavros and raised them as siblings, so they're hella tight. Since the Midnight crew is essentially a gang, they all grew up around violence. Sollux and Aradia try to avoid it as much as possible since it brings back bad memories for both of them. Karkat and Tavros are less effected by scenes of violence, but also prefer to shy away from it if possible.
Snowball: She adopted Vriska as her daughter around the same time as the Midnight Crew adopted their children, just to prove a point that she could raise a child better than they could. After Vriska paralyzed Tavros and got her arm blown off, and her eye blown out, she became a bit of a reclusive and only ever went to events she knew Terezi was going to.
Gamze has never gone on a killing spree, though he has on a couple of occasions harmed others when off of his prescribed weed.
Gamzee and Nepeta are in a relationship, because crack ships, am I right?
Nepeta and Equius are cousins and have always been as close as brother and sister.
Nepeta's family moved into a house close to The Midnight Crew's home base, so she also got to grow up with Karkat, Aradia, Sollux and Tavros. She and Equius were practically extended family.
Kanaya and Rose are obviously together, I could never split those two babies up. Though they are the exact same age as pretty much everyone else, they behave like moms almost. Constantly doting, wanting to know what's going on in their friends' lives. But they're always careful not to overstep their boundaries.
Karkat, Aradia, Sollux and Tavros are all known by their peers as "the Midnight Crew kids" since it's easier than saying all of their names.
Kankri, Latula, Mituna and Rufioh are distant relatives the Midnight Crew kids and will probably be mentioned every now and then as their cousins, though nobody really knows their relation.
Frigglish is a veterinarian who has taken Roxy under his wing to teach her the ins and outs of running your own business.
The Striders and Lalondes all used to live in the city but moved to a smaller town to get away from all of the "hussle and bussle" as Rita calls it. Dirk, Dave, Roxy and Rose moved along as well because some good colleges were in the area and they needed to make sure Davis and Rita didn't end up popping out another sibling.
Jake is like the kooky uncle to everyone here and please do not expect me to write too much into his character (I don't know why, but I just don't like him a whole lot. . . I think he feels just a little too dumb. . . maybe that's just me though.)
And that should pretty much cover it. The rest will hopefully be written about in the story so I hope you were educated! You may continue!