Readers love series. I do, too. It’s like visiting a bunch of old friends and catching up on what’s new in their lives. When readers pick up the newest book in an established series, they have an expectation of what they’ll be getting. Thus, it becomes very important to maintain consistency in both style and characterization. So there are numerous things you need to think about when considering writing a series.
The first thing is know your characters and know them well. Who is your protagonist and who are the members of his or her support group? Consider things very carefully. Once you start you’ll be locked in to what happens in that first book. Sara Paretsky once told me that she regretted making her protagonist, V.I. Warshawski, an orphan. To compensate Vic’s lack of family interaction, Sara created her surrogate mother, Lonnie Herschel. I recommend tossing around all the variables before you start, but sometimes, it’s possible to augment your cast of characters after you’ve established the series. Michael Connelly’s Harry Bosch, for instance, found out he had a half-brother long after the series was established. I recommend creating a character bible, and not only for your protagonist, but for every character. These bibles, aka character sketches, can be as extensive or brief as you see fit. But it’s essential that you keep those background facts consistent throughout a series, and there’s no better way to do that than creating and maintaining those character bibles.
If things are real complex in the life of your series character, you might want to consider making a flow chart. Since I recommend doing an outline, it’s apropos to mention at this point that if you do have an outline, your flow chart is already written.
Another thing you might want to think about is how many books you may want to write in this series. My own personal preference is keeping the total around six or seven. My Ron Shade series has been stalled at four, my Leal and Hart series at three, and the Executioner is in the four-hundreds. I can take credit for only eight of those, however. Ross MacDonald once said it was difficult to keep writing the same book over and over. He had a point, but the challenge is to make each book interesting and a good read. After all, fans buy each book in their favorite series because they have a certain expectation of the type of story it’s going to be. Give it each one your best effort.
If you have the hopes of writing an extended series there’s another important matter you need to ponder: should you have your character age chronologically? Sue Grafton solved the problem by setting all of her Kinsey Milhone novels in the 1980s. This way, Kinsey can stay at basically the same age in all the books. Sara Paretsky had her protagonist age more or less realistically, but that process has slowed considerably in the last few books. Still, you have to be careful associating your protagonist with specific events that will allow the readers to label him or her to a certain generation. Both Robert B. Parker and Mickey Spillane made their tough private dicks veterans of particular military conflicts. Spillane’s Mike Hammer talked about being in World War II in the early books, just as Mickey himself was, and Parker’s Spenser was in the Korean War. Both Spillane and Parker kind of let the ages of their heroes lapse as their series progressed. And when asked about the age of his famous protagonist, Travis McGee, the great John D. MacDonald replied with a smile, “He ages at a slower rate than the rest of us.”
So the bottom line on writing a series is think about it, long and hard, before you start.