u/Bandtrees

I'm usually a fanfiction writer, dipping into my first major original work. With fanfiction, there is the assumption the reader is familiar with the characters and the world they live in, relationships they have, etc., so that familiarity does some heavy lifting in terms of knowing these peoples' relationships and history. With making characters and relationships wholesale, I worry it doesn't feel authentic - I don't want to just tell the reader these characters are close and have known eachother for a long time/gone through a lot together, I want to express it, but I feel like bogging down the story with by the way, this happened! in narration or dialogue is cheap too, and I don't think the pacing would benefit from starting early enough in the story to show that history develop. There is a lot of discussion of this relationship by other characters that I think I portray well, but I want it to feel real in their proper scenes together, too.

So is there a way you express this authentically, making characters feel like they've been in eachothers' lives for a long time and have history? Is it a matter of body language? Rich POV narration? Other minutiae that I'm overthinking? I feel like things like inside jokes or referential dialogue or expository narration could be cheap, but it could also just be that all your writing feels cheap when you know how you write it x] Thanks!