have you ever read the god of small things by arundhati roy? it’s a really good book with really nice, casual prose. It’s also an extremely tough read because it deals with themes similar to what you’re working with. I’d try and pick up a copy if you can
I’d do two scenes right after one another early on in the book, with them interacting with each other and their peers at work, and then them interacting with one another in private. Treat them like character studies- those scenes should have v little plot information but rather work as character explorations to really lay out just how fucky these two characters are.
I’d also play up the shallow relationships they have with others and the fact that their only real source of emotional support is from each other. It’s kind of like a self fulfilling prophecy- they can’t trust anyone else, so their sibling relationship becomes twisted and because their relationship is so twisted, they can’t trust anyone else and because they can’t rely on anyone else they turn to each other which-