She is a cow and the former princess of the twonicorns who got replaced when she decided to become evil (sheโll still insist sheโs royalty though and will get mad if you donโt agree!)
Marius von Fundshauserโs father died when he was only seven, thrusting him into a position of great wealth, power and influence among the local upper crust at a young age while his grief was still raw. He also attends an incredibly elitist and traditional-sounding boarding school. Between these factors, he likely has a lot of experience with adults wanting to control, manipulate and exploit him.
He is romantically involved with Grenda, albeit mostly long-distance.
Grenda is one of Mabelโs best friends.
On the same night that Marius gets flicked in the nose by his soulmate, Pacifica cements her change of heart and becomes a friend of Dipper and Mabel.
She and Dipper are strongly implied to have potential for romantic involvement.
After Weirdmaggedon, the Northwests have lost a significant amount of money (though relatively still not that much) and their big fancy mansion, and Preston immediately swearing loyalty to Bill out of selfishness and cowardice probably damaged their reputation in Gravity Falls as well. Preston and Priscilla are exactly the kind of parents who would take out their anger and bitterness about this, and try to compensate for their loss of some control by, abusing their daughter even more.
They will do their best to sabotage her new support system and suppress her growing independence.
But you know who they could never turn away? And would recognize and be able to relate to their treatment of her? The richest rich boy in Richardson Richingtonโs Rich Boys Richcademy, thatโs who!
Conclusion: I need to write a fanfic about these two Pine twins-adjacent rich kids with parental issues and inter-class relationships and their inevitable beautiful friendship.