See Them as People, Not Functions
Flat characters weaken tension. Believable ones sharpen it. Readers remember the way a medic laughs in the dark, the neighbor who knows too much, or the mechanic who can’t stop checking exits. Those glimpses of reality are what make the world feel alive. So how do you breathe life into a cast that isn’t always in the spotlight?
Secondary characters aren’t props for plot—they’re people who happen to share the stage.
- Why it worksWhen supporting characters make decisions that feel self-motivated, they become mirrors, foils, and anchors all at once. Stephen King’s The Stand and Celeste Ng’s Little Fires Everywhere both excel here—every character has private logic and contradictions that ripple outward. The story’s shape changes because of them, not around them.
- How to do itWrite every side character as if you’ll need to spin them into their own short story later. What haunts them when the main character isn’t watching? What secret grudge or private hope would they never confess? Build that inner scaffolding early, even if the reader only glimpses it once. Then, when they step onstage, their choices will feel lived-in, not convenient.
Do
Let secondary characters act from their own moral compass, even when it complicates the protagonist’s path.
Give them flaws that matter—a nurse who avoids confrontation might miss a crucial symptom; a brother’s loyalty might border on delusion.
Avoid
Reducing them to one-note traits (“the skeptic,” “the comic relief”).
Using dialogue to summarize their purpose instead of revealing personality through conflict or contradiction.
From My Work
“’He’s fine,’ Sylvia said, her tone too steady. I checked Calvin’s forehead anyway. It was warm, not hot. Still, the pause told me what she didn’t.“
In Salt & Bone, Sylvia Torres starts as Lisa’s voice of reason—a paramedic-turned-caregiver. But her choices aren’t predictable. She lies to Lisa about Calvin’s temperature because she’s terrified, not cruel. That moment reframes her: not a “supporting” role, but a fully human one.
Let Relationships Define Depth
We understand who characters are by how they treat—and are treated by—others.
- Why it worksConnection builds texture. The late Toni Morrison wrote that “definitions belong to the definers, not the defined.” In fiction, the way others perceive your side characters is part of their reality.
- How to do itAnchor secondary characters in social truth. Who listens when they speak? Who interrupts? Who trusts them, and who doesn’t? Use those reactions to imply reputation, power, or vulnerability. It’s quieter than exposition and infinitely more believable.
Do
Show relationships shifting under stress—how a side character argues, forgives, or walks away says more than backstory ever could.
Avoid
Keeping their emotional lives frozen once the protagonist’s arc moves forward. The best supporting cast evolves, even if they drift out of frame.
From My Work
“You look like you owe the world an apology.”
In The Death of My First Assignment, Martin’s bartender doesn’t need a monologue to earn credibility. Her one line tells us as much about her as it does about him. She becomes a conscience wrapped in sarcasm, visible for two pages but felt for ten chapters.
Give Them Stakes of Their Own
If every side character vanished tomorrow, what personal crisis would remain unresolved? That question keeps them real even when they aren’t on the page.
- Why it worksThe illusion of off-page life is what separates stories that breathe from stories that perform. Cormac McCarthy’s The Road achieves this through absence—characters are defined as much by what they’ve already lost as by what they still carry. When you sense that others are living and dying just outside the frame, the world feels infinite.
- How to do itWrite “exit scenes” as carefully as introductions. When a side character leaves the main thread, show what they’re walking toward or what’s pulling them away. Even if readers never see that journey, they’ll sense its weight. A believable character is one whose story continues without you.
Do
Allow supporting characters to make irreversible choices. Let them fail. Let them change their minds.
Avoid
Treating their presence as utilitarian. Readers can tell when a scene partner exists only to deliver exposition or set up a punchline.
From My Work
“I slid the controller across the floor. Brendon didn’t move. The blue light from the TV flickered across his face—dry eyes, slack jaw, the look of someone who forgot how to exist.”
In Salt & Bone: Ashes, Brendon begins as comic relief, riffing with Jack to cut tension. But later, when he opens up about his losses, humor becomes his defense mechanism. His arc fractures in silence. We believe Brendon’s grief because it’s not tidy—it exists even when he’s off the page.
Final Thoughts
Every writer knows how to build a protagonist. The real craft lies in everyone else.
When your side characters carry private stories that could bloom without you, readers stop seeing cast lists—and start seeing people.
Extras
- Read about Salt & Bone (WIP)
- Read The Death of My First Assignment (Amazon)
- Sign up for the newsletter to get weekly tips
- Stephen King’s The Stand
- Celeste Ng’s Little Fires Everywhere
- Beloved by Toni Morrison
- Cormac McCarthy’s The Road