Books that feels like the writer have confidence in the audience’s competence/comprehension

I'm looking for books with a certain narrative style. A range of casts who have an established relations or history with one another that we, as the reader, personally don't get to see how that relations came to be. Where the characters are interwoven, not only with each other but with the past and with the world. A story that doesn't open with a metaphorical "Once a upon a time", that we have to learn the lore through context clues. A kind of narrative that trusts the reader to be smart enough to piece two and two together instead of having to hold their hands and walked them through every definition.

Could be high fantasy, low fantasy, horror, gothic is always welcomed—really any genre as long as there is little to no romance (or romance as a subplot if there's any).