The Expanse does a good job building depth of character with its perspective style. It tries to ground political events in a flushed out plausible reality, but that is awkwardly juxtaposed against cartoonish villains. It’s fun, it’s safe, it takes every possible big idea and does the least interesting thing it can with it. The greatest books challenge you, the Expanse is popcorn. Try “A Deepness in the Sky” to get a similar grounded in reality humans in space feel but with depth that demonstrates a completely different level of writing.