I enjoyed the realpolitik of Expanse but hated the trite interpersonal conflicts which seems to be a mainstay of modern drama. I find the main characters to be rather childish.
They are written in a childish manner: the white knight, the highly assertive love interest, the sociopath who wishes he could be a good guy, and the cowboy. Their personalities are unrealistic in ways that I would attribute to a young teenager. That said, the quirks of these trope-like characters is sometimes amusing. I enjoy the series mainly for the protomolecule plot, despite the characters.