There are clear structural differences in writing series books. I am, currently, writing the middle book in a tight trilogy. This entails not only keeping the plot of the book in mind, but the beats to set it properly within the short series. In this case, I can’t make it longer. The series needs to have a clear definitive end, because to come back later and plunge the characters back into the conflict would be a profound betrayal of what they had to do to win. Pulling the rug out from under them. It would hurt them, the readers would hate it, and frankly so would I. I won’t give them hope, only to yank it away and write another book. Betraying their trust would break the compact with my readers, make me very unhappy as an author, and the downstream consequence is that I would lose readers and struggle with writing as I fought my own brain which would be pouting at me for that betrayal.

I am planning, once I finally finish this book (it’s taking rather longer than I’d planned), to write an installment in another series, this one an open-ended series. That is a beast of a rather different shape and size. Plotting those books is… interesting. For one thing, when I started the Groundskeeper with a short story, I had no idea what it would grow into. For another, I still don’t know that there will be an ‘end’ to that series. I suspect that at some point in the future I will reach a point I don’t care to write past. If I see that coming, I can give the readers satisfaction by tying up any loose ends, delivering a warm farewell, and letting it fade into the sunset. Alma Boykin, our own TXRed, is doing this currently with her Familiar books, and I am observing while taking notes.

The goals for each kind of series can be very different, and that will shape the books which make up the parts of the whole. In a tight trilogy, everything needs to move the overarching plot along. In the looser mystery series (which is what the Groundskeeper truly is) each book can and should stand on its own two feet. The tight-series book I’m working on, book 2 in the BOHICA series, leans heavily into book 1, and book 3 will be even more so. Because the plots are intertwined to an ultimate conflict and shared goal for the characters. Now, can a planned trilogy become a longer series? Absolutely.

So how does a planned trilogy turn into five books? Even when working from an outline, you can have things you realize should be written differently. Sometimes this can mean that what you thought was one book is really two. Sometimes that’s for the practical reason that a book over 120,000 words should actually be two books. Maybe even three… But that’s a different post, one about the business of publishing, not the art of writing series. Write the story, worry about length later. If you write it too long, you can always break it and publish in rapid tempo.

I have finished two trilogies. Both of them have spin-off works, in different ways. I plan to revisit the worlds again, for the Tanager series by writing Julia’s stories, and for the Underhill series to tell stories about the children of Pixie for Hire (the core trilogy) and other characters from those books. From a marketing standpoint, it’s very difficult to market an unfinished series. It’s also something you want to consider when you start a series (I did not, and it is biting me in the behind now). Starting a series with short stories that gradually build into novels is, I think, not uncommon. It is, however, not what a new reader wants to see. They want full novels. Due to my lack of planning I’m faced with needing to adjust series numbering on two series, at some point, which is going to be awkward at best. Don’t do that to yourself. I didn’t even know I was writing a series when I started those – the characters hijacked my brain and insisted on more – but I learned from them that I shouldn’t do that.

How have the rest of you handled the difference between a closed arc and an open-ended series? Especially if the characters decided the plan for you.

Off topic: I’m turning my essays on writing into a bite-sized podcast, for those of you who enjoy that sort of things.