Through reading, I've discovered quite a bit more about writing. More specifically, I've been working through The Story Grid by Shawn Coyne and Nobody Wants to Read Your Sh*t by Steven Pressfield (yes, I'm reading through it again to internalize the information.)
They both talk about Genre Conventions. Piece of a genre story that if left out of the narrative, would make the book feel incomplete. Example: Romance stories would feel incomplete if the couple never faced trials.
Another example of this comes from my own experience.
Doc Holliday's ongoing feud with Johnny Ringo in Tombstone is one of my favorite movie experiences. The first meeting is iconic with Doc openly mocking Ringo.
The build-up between them is dramatic throughout the movie, especially with Doc's illness, reputation with a gun, and penchant for mocking his opponents. In the end, the two must duel. That's the promise made by their first encounter and each subsequent one.
The story would be incomplete if the two didn't meet and shoot it out. The build-up between them, their meeting in the street cut short, the moment in the bar where Ringo drew on Doc, would have been wasted story-telling if Doc had let Wyatt Earp go to the meetup with Ringo instead of sneaking out to duel the Cowboy himself.
Story elements like this might seem cliche, but they work.
The good cowboys win - Western. The couple gets together - Romance.
Picking a genre is making a promise to your reader about what the story will give them. Your book cover also makes a promise.
It doesn't mean your writing or the story line has to be cliche. In fact, the fun part is figuring out a new way to present the story while still maintaining the genre conventions.
But promising your readers and delivering is how you create a good reader/author relationship.