Write until the story’s done. Then stop.
There are plenty of series that have gone on too long. Jumping the Shark is a trope for a reason. When people get greedy or don’t realize they’ve run out of ideas, series end up not just losing quality, but failing in general. My wife and I often joke that Ross stopped being a character somewhere around season four of Friends. (Your mileage may vary.)
It’s not just tv series, of course. Book series can run on for literally hundreds of books. It’s the common wisdom of the day that series sell better than stand-alone novels, so why not set up a series that lasts a long time?
True, some readers love that. Of course, then you run into the problem of having too many books. The Honorverse has a great start, and I’ve heard it continues in fantastic ways, but… there are just too many books. I haven’t read farther than the first book in the series because of that. It’s intimidating!
So, how do you know when to end?
When the story’s done.
How do you know what the story’s done? Well, I guess you need to ask what your story’s about. What journey is the protagonist on? What is she meant to become or learn or accomplish? If you don’t know that and you’re writing it, time to sit down and figure it out. If you don’t know, you’ll never be able to finish your story because you’ll still be looking for it!
I haven’t written many book series… but what I have done is outlined the entire series, front to back, before penning even a page of book one. I wanted to know not just where the characters start, but where they’re headed. Only Dragons of the Ashfall is currently published of one series, but I know how everything wraps up. The end of book four will hopefully leave readers teary-eyed and wishing my death. It will be an ending, though. There will be no further books in that saga. Maybe I could write more stories within that setting, but that particular story will be complete. (Book two is completely written and currently sitting with my publisher!)
It’s the same for Madelyn of the Sky. It’s six books, but I knew how that story would end before I began. Madelyn begins as a cocky hero who’s not actually all that sure of herself. She’s got her Grandma and her friend/ older sister, Renity. Along the way, she’ll find real confidence, find more friends, lose others, and discover what her power really is.
But by the end… well, there’s a reason the tagline of book six is, “Her world will end.” I knew I wanted a definitive ending for this saga. The story will be done.
Now, I already mentioned that there are so many other stories I want to tell in this setting. But those stories… won’t be Madelyn’s. Her tale is complete when you reach the last page of book six.
No more sequels. No jumping the shark.
One complete story in six volumes.
By the way, there’s less than a week left in the Kickstarter campaign for Madelyn… care to take a look and back it? I promise, you’ll get a story that has an ending!