It's interesting to think about the unspoken (and certainly unwritten and unenforceable) contract between writer and reader about who will maybe die and who will definitely live, and who will partner up, and so on.
I've been reading a sci-fi/romance novel, and it drove me crazy that the protagonist ended up with the guy, because the guy in question was a manipulative creep (who didn't even express any remorse or intention to change at the end).
But the marketing included the word "romance," so I knew they'd end up together (I kept hoping that a triangle would develop, but it never did).
I remember there was one Julia Roberts movie where she set her sights on a guy and didn't get him. There was some outrage, as I recall, though I imagine Julia Roberts herself might have had this experience in her life at some point.
This is why I never identified Stevie One as YA, though certainly the bare bones description of the story has a very YA-ish sound. But the general expectation many readers have about YA would probably have leaned toward less smoking, more (or any) romance for the protag, and fewer lesbians.
In mystery fiction, for example, part of the bargain is that the detective will solve the mystery (and survive), and if you're going to go in another direction you're going to have to work harder to make it pay off. However, several great mysteries have been written where the detective turns out to be the killer, for example, or one of the victims, as in The Burning Court.
This applies in all fiction (in different ways), and I'm not saying it's a bad thing. There are certainly characters in my writing who will not die. But I think it's important to look critically at these assumptions – these non-binding obligations – rather than just following them. Because, if you break the "rules" and do it right, you can create something pretty terrific.
By the way, the title of this post comes from this quote (about a novel) from The Importance of Being Earnest: "The good ended happily, and the bad unhappily. That is what fiction means."