Guest post by Beach Reads and Deadly Deeds author Allison Brennan
New York Times and USA Today bestselling author Allison Brennan believes life is too short to be bored, so she had five children and writes three books a year. A native of northern California, she moved to Arizona with her family and pets in 2019 and now calls Phoenix home.
About Beach Reads and Deadly Deeds (out 17 June 2025): In this sun-dappled mystery from New York Times bestselling author Allison Brennan, a risk-averse bibliophile gets in over her head when strange notes in a book draw her into a real-life investigation.
Crime fiction has always delivered an abundance of memorable secondary characters. In romantic suspense, it’s often the love interest. In police procedurals, there’s the indispensable partner. In domestic suspense, the loyal best friend usually has your back — until they don’t.
In my romantic mystery Beach Reads and Deadly Deeds —my first full-length story written in first person— I spent every moment in Mia’s head. That was a challenge for someone like me used to juggling five or more points of view per book. It made me think carefully about how secondary characters appeared through Mia’s lens — and how I could bring them to life without giving them their own chapters.
My favorite of these characters is Brie Locke, an 18-year-old on the brink of college, uneasy about her father’s new relationship. Mia is 30, and that twelve-year age gap initially felt vast. But I thought of my own daughters—nearly ten years apart — and how shared values and lived experiences can bridge even wide generational divides.
Brie is self-assured, but nervous about leaving home. Mia is confident professionally, but uneasy in social settings. Brie is a Gen Z social media whiz; Mia sees technology as a necessary tool she only half understands. Both were raised by single dads. Yet where Mia is cynical about love, Brie holds tightly to the memory of her parents’ happy marriage. Their dynamic evolved naturally, and their bond added depth to the story — a warmness I didn’t really see until I was done writing the book.
Of course, working together to solve a murder and trying not to get killed in the process tends to accelerate friendship
And I think writing Brie as Mia’s friend helped balance Mia’s budding relationship with the hot bartender Jason Mallory, who I also had a lot of fun developing!
Other side characters also interested me as I developed them through the story — Luis, the cryptic wise man; the wealthy but aggravating suspects; and especially Anya, who’s haunted by a past decision that could destroy her. And I can’t forget the horny honeymooners who showed up when Mia least expected them! Each added texture to the story, but it got me thinking: what makes a great secondary character?
Here are some of my favorites from other books I love:
The Partner
PI Elvis Cole wouldn’t be the same without his partner, Joe Pike. In Robert Crais’s series, Elvis is usually center stage, but in The Big Empty, Pike shines. Their enduring friendship and loyalty are always present, but this installment brought their bond to the forefront. It’s my favorite since Taken.
Also Crais is Suspect, a powerful story about LAPD Officer Scott James recovering from a traumatic shooting—and the bond he forms with Maggie, a military dog also suffering from PTSD. Their partnership is raw, healing, and unforgettable. It’s one of my top ten books of all time.
The Bestie
I’m currently reading The Ex-Girlfriend’s Murder Club, a darkly fun tale of three women who all dated the same man — now dead. Watching their unexpected friendship develop amid chaos is one of the best portrayals of female friendship I’ve read in a long time.
Then there’s Vero, from Elle Cosimano’s Finlay Donovan series (starting with Finlay Donovan is Killing It.) Vero is technically the nanny, but she’s also the bestie/partner we all wish we had. She’s younger than Finlay, fiercely loyal, brilliantly blunt, and hilariously fearless. Whether you call her the sidekick or the best friend, she steals every scene—and a piece of my heart.
The Sidekick
Flora Dane from Lisa Gardner’s DD Warren series might not fit neatly into the sidekick box—she’s not quite a partner, not exactly a friend—but she’s unforgettable. Her tragic backstory and the way she channels her trauma into strength make her one of the most compelling recurring characters in modern crime fiction.
In Gregg Hurwitz’s Orphan X series, we meet Joey in Hellbent, a teen-age hacker who not only keeps up with Evan Smoak, but often surpasses him. She adds emotional depth and even serves on occasion as Evan’s moral compass in a world full of gray.
Then there’s Nate Romanowski from C.J. Box’s Joe Pickett series. Joe is the moral heart of the series, while Nate—his occasionally violent, always fascinating friend — challenges those morals at nearly every turn. He’s more than a sidekick he’s the wild card that keeps things unpredictable.
The Cast of Thousands
J.D. Robb, the alter-ego of prolific author Nora Roberts, created an amazing world in her In Death series, set in near-future New York City. At the center are Detective Eve Dallas and her husband Roarke, the richest man on or off planet. But the supporting cast makes the series shine: Peabody, the loyal partner; Feeney, the curmudgeonly father figure; McNab and his outrageous outfits, the tech whiz kid; Mavis and Leonardo; Summerset, Roarke’s majordomo and Eve’s nemesis-turned-ally. I could list many more characters I adore, but it would take a full-length essay. Every book feels like returning home to a vibrant, complex world.
For a lighter but equally delightful ensemble, Lucy Score’s Riley Thorn “Reluctant Psychic” series is pure fun. From the quirky octogenarians Riley lives with to her drama-filled family and her boyfriend Nick, the characters are hilarious, heartwarming, and endlessly entertaining. Every new book layers on more chaos—and more charm.
I’ve been accused (often fairly!) of filling my thrillers with a few too many characters. But for me, these relationships—the partners, the besties, the unexpected allies—are what bring stories to life. I’m a work in progress, but I’d rather have too many vibrant personalities than not enough.
One of my favorite things about writing Beach Reads and Deadly Deeds was that I wasn’t tied to any of my existing characters. Each new person developed organically as they appeared on the page, bringing comic relief, intrigue, flair—whatever the story needed. It was both liberating and a little terrifying!
So tell me — who are some of your favorite secondary characters?
