I wrote many series, some as short as two books (the Archangel twin books), others as long as eight novels (like the CURSE OF THE LOST ISLE, based on Celtic legends). New authors, and sometimes readers, ask me how long a series should be. There is no universal answer to that question. A series, like a book, should be as long as needed to tell the whole story.
The number of books also depends upon the characters.
If they are the same characters throughout the series, is each novel a continuation of the previous book? The author cannot hold the reader without resolution indefinitely. That is how some TV series that started strong lost their momentum when the writers dragged the story too long before offering some kind of explanation or resolution.
On the other hand, if each novel is a complete story, the series can go on much longer. A few authors have successfully published dozens of novels in the same series that way, some were later adapted for TV series, like Tess Gerritsen’s Rizzoli & Isles. Harry Potter also comes to mind, but as it features children, and children do grow up, that series was limited from the start. As for characters like James Bond, they can probably go forever with many different incarnations as each generation gives it a different twist.
My longest series (eight novels) is The CURSE OF THE LOST ISLE, based on Celtic legends. Since my ladies are immortal (related to Morgan the Fay), they reappear in different times in history. The first two books tell the story of Pressine the Fay. In book two, she has three daughters, subsequently featured in the following books. Melusine the Fay has four books, as she appears in different places at different times in history (books 3-4-5-8). Her sisters, Palatina (book 6) and Meliora (Book 7) each have one story to tell, so they only have one novel.
Another technique is to write shorter series, related to each other. Three books is considered a happy number for a series. Easier to commit to for the reader. Some readers also like to only read series that are complete, as they do not want to wait until next year for the next book. The reader who enjoys a three-book series, will likely pick up the next series set in the same world they enjoyed the first time, like the Star Wars universe.
This is the case for my BYZANTIUM series and AZURA CHRONICLES, set in the same universe with a few crossover characters. Byzantium is a space station, and Azura is a planet, existing in the same universe at the same time.
Most of my series novels are standalones, and the reader can pick up any book and thoroughly enjoy it without missing anything. Then he/she can go back and enjoy the other books as well, even if not read in the chronological order. But if you are like me, you’ll want to read them in the right order to fully appreciate the arc of the bigger story behind the novels.
On that note the first book in each of my series is currently discounted to $1.49 in kindle on amazon.
Enjoy the discounted reads!