Sometimes a character or storyline is so compelling, or becomes so prominent, that a spinoff book or series begs to be created. And other times, a spinoff is pointless or overkill.
In my early days with my Atlantic City characters (1991-3), I had so many spinoffs going, and many more planned. At my height of planning spinoffs, I had at least 14 spinoff books or series planned or in progress. Today, I only have three—the four introductory books (1938-41); the series focused on Max and his family, with a fair bit of focus on Kit’s family as well (1941-70); and my 12-volume handwritten magnum opus about Cinnimin and her descendants (1941-2050).
The original series (1941-50) is now permanently shelved, and I no longer want to write a mini-series about their college years (1950-4) and a longer novel about their lives in 1955. I also cut my losses and stopped the spin-offs in progress, and abandoned my plans to create all those other spin-offs.
This was a case of way too much material about the same people, in the same timeline, with way too much overlap between series and books. There are only so many ways one can write about the same events with a different focus, and original material for each book so it doesn’t become essentially the same story ad infinitum. If you love your secondary characters or members of an ensemble cast so much, pick just a few to focus on, and spin them off. Not every single character. And make the arc and storylines of each distinct, not just the same events with different people at the forefront.
I decided to spin off the stories of my Shoah characters (during and after the War) from my Atlantic City books because they were just getting too long and detailed. I had a folder full of files of stories and wraparound narrative segments about eleven different characters or sets of characters, several of them comprising three to five files. My original intent was to periodically insert this material into my Atlantic City books set at the same time, as a sort of alternate trajectory and sobering counterpoint to my American characters’ adolescence.
That originally worked fine, but once I began writing separate files of stories for future insertion, they were no longer just a few paragraphs here and there. They took on the character of potential novels. And my 12th Max’s House book, the most recent one I’ve worked on, has several chapters or long sections of chapters just about the European characters. That really pulls the focus off the original spotlight characters, and splits the narrative up too many ways. My Atlantic City books tend to be under 70,000 words. They’re not meant as grand, sprawling, epic novels with all these disparate story threads ultimately tied together.
It’s time for a spinoff when a secondary character or storyline suddenly starts assuming so much time and prominence that you’re spending less time with the intended main characters and storylines. If you easily have enough material to flesh these former side stories out into full-length novels, that’s an excellent sign that it’s time for the books to converge.
I grew up when series books for young people were really popular, like The Babysitters’ Club and Sweet Valley High. Those series had inordinate amounts of spinoffs, and clearly it was more about quantity over quality. Was it really necessary to write a series about a main character’s bratty little stepsister, a mystery series, a super-specials series (about summer vacations, trips abroad, etc.), books about popular secondary characters, a super-mysteries series, autobiographies, a series about a character who moved away, a series about the classmates of the obnoxious stepsister, and a finale series?
Your fictional world shouldn’t be treated like a cash cow, either before or after publication. Spinoffs should only be undertaken when there’s something really compelling about secondary or peripheral characters and storylines, not because you want every single character to get a turn in the spotlight. Too many spinoffs can ruin the series.