Pandemic Audio: Leviathan Wakes by James S.A. Corey, 2011, downloaded from Wisconsin Digital Library.
I started watching The Expanse TV series on Amazon earlier in the pandemic. I enjoy the show, it is very well done. So, why not try the book?
Result: the TV show is actually more in-depth for the characters and politics and details of life in space or low gravity. I'm guessing that later novels in the series cover the same time period but with different characters and that the TV show blended all those characters into one narrative. That's a guess though.
Anyhoo. Space has been colonized. Mars and Earth have been feuding for decades and narrowly averted a disastrous war about 10-20 years ago. Mars is not a military dictatorship but their society has been built upon a single goal of terra-forming Mars. Kinda like Israel with kibbutzes and the strong drive for self-defense.
Earth is overpopulated, has one government, and looks down on the martial Martians and the Belters.
"Belters" live in the low-gravity asteroid belt or on the moons of outer planets. Belters mine for the water and other resources needed to survive outside Earth. They looked down on by the Martians as well as Earthers.
Mix it all up and you've basically got colonists and imperialists fighting over resources, government representation and limits of authority, and independence.