Luna: New Moon by Ian McDonald.
Generally characterized as A Game of Thrones in space, which isn't a bad way to put it. I think in a lot of ways it's better understood as a modern counterpoint to The Moon is a Harsh Mistress that carefully examines and dissects Heinlein's libertarian rhetoric, while also adopting and pushing even further forward his imaginative considerations on what future social dynamics and sexual politics might look like.
It's also, just, an absolute hell of a political thriller. Assassinations, arranged marriages, coups and counter-coups, and court cases that can turn into trial by combat. It's fun, it's brilliantly written, every character is well developed, and no one comes off as a villain or a hero (apart from Bryce. Fuck Bryce.)