The Abyss is not a nice place. It has all the worst aspects of modernism thrown in with some good old fashioned hell symbolism. It's a cruel, inhuman, vindictive environment, and to be honest Jessica and Izah'belya are both victims of their society. Jessica is an outsider, and the only way she's found respect is by attaching herself to outsiders (because, socially, there's a niche for people like her there), and Izah'belya is in the system and gets the benefits in return for being trapped in an abusive set-up where her mother [1] sets all her daughters against each other so none of them have time to eye up her throne. She can't ever show weakness, and if any of her and her half-sisters look like they're getting too attached to each other, their mother sets them against each other directly.