What promises are you making to your readers? What does that even mean? It’s not like you signed a written contract. You didn’t pinky swear to tell the reader what happened to that character who disappeared mysteriously in the first chapter. You’re under no obligation to include that, right?
Actually,… I guess it was an implied pinky swear ’cause you kind of are.
Readers rely on the foreshadowing and puzzle pieces that build the plot. The details of the everyday activities and worldbuilding, character traits and behavior, plot arcs – almost any information you put into the book from the first page counts as a sort of promise to the reader. A lot of yours should be specific to your world and story, but some are universal.
Promises You Make Your Readers
1. If you start a story arc, you’re going to finish it.
If you introduce a mystery, even a subplot, (what happened to Sir Henry’s boot?), then the reader expects it to be solved by the end of the book (or the series at the very least). With the way books like to tie things together, readers might even expect the little mystery’s resolution to link to the main plot, too. So if you leave them hanging about something, expect to hear about it later.
2. Characters won’t change without a reason.
What a character is like, what a character likes – it can’t change on a whim between the first chapter and the last one. If you make a character sneaky and unreliable, the reader expects that character to stay sneaky and unreliable until/unless some actions show otherwise.
3. The World operates under specific rules.
How does magic work? What level of technology is available? These are the sorts of questions you have to answer in your worldbuilding, but once they’re established, you’re stuck with them. You can’t say that there’s gravity in this location in one scene and then contradict yourself in another.
Well, technically, you can, but you shouldn’t. Not if you want to keep readers (and make a good story).
That’s the crux of the promise issue. Think of it like a person. Jane. If Jane breaks one promise, we might give her another chance if it wasn’t too big a promise. We might even be generous and let her break a couple little ones. If she breaks a lot of promises (small, medium, and large) or a few really big ones, the only way we’re sticking around her is if she’s related – and maybe not even then.
So you might be able to leave a tiny mystery unsolved without losing readers. You might be able to change the color of a character’s eyes between the first chapter and last – if it’s a non-plot-central continuity error like that, then you might even be able to change a rule of the world. If you do all 3? You’re pushing your luck. Especially if any of it directly involves the main character(s).
After all, breaking those rules or defying what you’ve said before is like telling the reader to ignore what they read before: “That’s not important. Forget that.” And as a reader, my response would be, “Then why did I read it?” in an disgruntled grumble. And I’m not the only one.
Readers don’t like broken promises. That’s all there is to it. And you can’t get around it by not telling promises – without promises, there’s no story. So if you want to keep people happy and make your own life easier, try to keep the promises you make your readers. Better yet: succeed.