In Eddie’s Boy (Mysterious, Dec.), Perry’s fourth crime novel featuring Michael Schaeffer, the retired contract killer must ward off attacks that are linked to a job he did decades earlier.

When The Butcher’s Boy was published in 1982, did you envision it as part of a series?

I’ve always thought of each first book in a series as a single story that was intended to be complete in itself. A second volume becomes part of the plan only after the first one is finished, but hasn’t told the whole story.

Why so long between each subsequent installment?

I’ve always tried to avoid writing series. But in the case of The Butcher’s Boy, I may have set the series in motion once I made the killer my own age and physical description. Ten years after The Butcher’s Boy, I had changed; I was a bit more wily
and a better liar than before. So I wrote Sleeping Dogs, the second book, because I was curious about what Michael would be like at the same age. Nineteen years later, my agent suggested writing a new Butcher’s Boy story that might inspire a TV series. When it was finished, I decided to expand it into a novel, which became The Informant.

What inspired Eddie’s Boy?

My wife suggested that I write a prequel about Michael’s childhood and youth. What I ended up with was a novel in which he gets through more terrible trouble recalling strategies that his father, Eddie the Butcher, taught him 50 years earlier.

Where do your characters come from?

All of the characters in my books have two origins. Part comes from pieces of people I’ve known, or at least observed. I think about a character until I can hear him or her talk—the expressions, the vocabulary, the sound of the voice. The second part of a character’s origin is me. I think when we write a story, we take over and inhabit each of the characters.

After all these years, do you find more pleasure in writing a series entry or a standalone?

I’ve learned to appreciate the pleasures that come with each kind of book. I still love the excitement of beginning a story about all new people confronting new problems. But there’s a different kind of good feeling about returning to check on a series character. I find that I miss some of them after a time away, and that I understand things about them now that I didn’t originally because I hadn’t lived enough yet.