I wonder if this person’s gonna stop watching the MCU, too. Pretty sure there’s no “actual ending” planned for that. Or the James Bond franchise. I mean, how does somebody like that watch television? Did they wait seven years to make sure Elementary would get an “actual ending” and not be cancelled between seasons like so many programs?
It’s funny because we’d just been talking about this at the Writers Coffeehouse last week (or two weeks ago at this point, I guess). How do you approach writing multiple, connected books? And one thing we talked about a lot was how the books are connected. Because that’s going to have an effect on how I write them and the stories (or story) I end up telling..
…and then we spun off onto a bunch of usual segues.
Now, I’ll warn you right up front, there’s not going to be a lot of “how to” in this post. As I’ve said here a bunch of times, writing’s a very unique process. You don’t write the way I do, I don’t write the way she does, she doesn’t write like you. So adding another layer on to that—find the best way to do this that works with the way you do that—is just going to be too much. It’s variables on top of variables.
What I’d like to do instead is throw some terminology at you and maybe some thoughts about how we can define some of those terms. Less instruction, a little more food for thought. Things I should keep in mind when I’m sitting down to smack my head against the keyboard.

Let’s start with a series. Simply put, this is an ongoing, open-ended collection of books or stories, almost always involving the same protagonists. If you think of a television series, that’s pretty much the same idea. I want every book to end with the potential of another book. It’s also not uncommon for these books to restore the status quo for our characters at the end, leaving them pretty close to where they began on a personal level. It’s why a lot of series get scoffed at as “plot-driven”–because not a lot happens with the characters on a story level.
You may have heard me mention that term before—series potential. That’s what we’re talking about. Each book could have—but doesn’t need to have—another book after it. If you stopped reading with this one, you’d probably be fine and feel like you’d read a complete story. But if I told you there’s another one, your first reaction shouldn’t be “What? How?!?” Editors love books with series potential. Seriously.
The trick here, of course, is it means I have to wrap up this story while also leaving space for another story. There’s a reason we’ve never seen a Bond movie that ends with “and peace reigned forever after.” And why we always see Jack Reacher wandering out of town at the end of every book.

The other key thing, I think, is the story itself. I don’t want to plan out a trilogy when I really only have enough story for one book. Or plan on seven when I’ve only got enough for three. You get the idea. Despite the multiple books, we’re talking about a set, self-contained story, so I need to be honest with myself about how much story I’ve really got.
Again—sorry to be repetitive—I’m just using trilogy as an umbrella term for a single story told over a set number of books. I want to be clear because it’s a term that gets slapped on to a lot of different things and, to be honest, I don’t want to read someone’s six paragraph spiel in the comments about how valid duologies are or that, no, that ISN’T what a trilogy is because abcxyz.
The important thing to remember here is that story universes rarely start out as such. They usually begin with a single series or trilogy, but then popularity demands a sequel or a prequel or a spin-off or what have you.

One last thing. Now that we’ve got these three broad definitions, let’s talk a little bit about exceptions. Well, about why I’m not really going to talk about them.
While there are times these three groups might overlap, the simple truth is it’s a much-later-in-my-career sort of thing. We have to acknowledge these exceptions happen after I’ve established my norm. It’s just not something to be thinking about at an early stage of my career. Believe me, if I walk in to my first (or second, or third) meeting with a publisher saying “it’s a trilogy of trilogies set in a shared universe with…”
Well, honestly, I can probably say whatever I want at that point because the odds are pretty good everybody’s already tuned me out. I’d written ten fairly successful books before I got to say “I think this one’s going to be set in the same universe, but isn’t really going to be part of the same series.” And even then, it kinda made some people uneasy.
Until then, go write.