How to Write an Amazing Detective in a Mystery

Abi Wurdeman
December 12, 2023
How to Write an Amazing Detective in a Mystery

Meticulous and mustachioed Hercule Poirot. Grounded and brilliant Isaiah Quintabe. Warm and clever Jessica Fletcher.

A thrilling puzzle may be the key to hooking mystery readers, but an intriguing detective is what reels them in for an entire series. And crafting appealing characters like Poirot and Quintabe isn’t as easy as it might seem.

The most successful literary sleuths have more going on than the crime they’re trying to solve. They have complex inner lives, strong opinions, and distinctive quirks. To complicate matters further, they manage to fulfill genre expectations while putting a new twist on familiar tropes.

If you’re hoping to create a detective character your audience will love, keep reading. You’ll learn:

  • How to craft a sleuth that fits your subgenre
  • Character development tips
  • How to simultaneously embrace and subvert detective tropes
  • How to use the mystery to bring out your sleuth’s character (and vice versa)
  • The key relationships in detective fiction
  • What your mystery protagonist’s arc should look like

Let’s start—as one always should—with knowing your genre.

What Readers Look for in a Fictional Detective

When you set out to write a mystery novel, the first thing you want to do is research your subgenre. Read the current bestsellers. Scan Amazon reviews. Haunt a few forums. 

This will reveal a lot about reader expectations. Each mystery subgenre embraces a handful of tropes that inform the sleuth’s personality. 

That doesn’t mean you have to write a cookie-cutter detective. We’ll talk about how you can bring a splash of creativity to familiar characters in a bit. But before you can subvert the norms, you have to understand them.

Classic Mysteries

Classic mysteries love the Great Detective trope. This person has exceptional deductive reasoning skills, champions facts over feelings, and is often a private detective or amateur sleuth.

Cozy Mysteries

The cozy mystery subgenre is famous for featuring female detectives of a certain age. They’re typically amateur sleuths who love baking, knitting, or brewing tea. But these are not hard-and-fast rules.

What matters most is that a cozy protagonist is good-natured, has no major vices (though flaws are essential), and gives off strong Common Person vibes (aside from the crime-solving thing).

Police Procedurals/Crime Fiction

This is where you get your Hardboiled Detective—the persistent and cynical sleuth who has little faith in humanity but still wants to see justice served. They’re almost definitely haunted (and motivated) by a cold case or a crime that affected them personally.

Serious vices are optional. Flaws are mandatory.


The protagonist of a noir novel is similar to a crime fiction detective, only darker, more cynical, and more self-destructive. These main characters rarely evolve enough to save themselves, though they will take huge risks to get one more criminal off the streets.

Balancing the Expected With the Unexpected

A person in a pin-striped suit and purple sunglasses looks through a magnifying glass.

So, how far can you stray from those beloved detective archetypes without upsetting readers? 

As you research your subgenre, you’ll start to understand why those tropes are so well-loved. Crime fiction readers appreciate the grit and complexity of a cynical detective who’s always on the edge of burnout. A light-hearted sleuth keeps cozy mystery fans focused on the puzzle rather than pondering humanity’s capacity for evil.

Understand what the most beloved gumshoes in detective fiction provide for their readers. Then see if you can put a twist on tradition without compromising that core benefit.

Here are some examples. 

The Sure and Steady Detective

The average fictional detective is clear-headed, even-tempered, and cool in a crisis. This establishes the sleuth’s crime-solving credibility and makes them instantly impressive to the reader.

You can toy with this trope by allowing your detective to be anxious or distractible in very specific ways that either don’t affect the investigation or ultimately help them solve the crime after a few blunders.

Adrian Monk (Monk) is a Great Detective with unparalleled powers of observation because he’s extremely attentive to details due to OCD and a long list of phobias.

The Haunted Detective

If you’ve read a few mystery novels, you’ve likely encountered a fictional detective who’s haunted by a past crime—a cold case or criminal act that affected them personally—or a broken relationship, like a child they can’t connect with or a romance they were too damaged to maintain.

To put a twist on this one, consider tormenting your sleuth with something completely unexpected. Maybe they once put an innocent person behind bars and now they’re obsessed with getting their facts right. Or perhaps what ails them is something heartbreakingly relatable.

In the Thursday Murder Club series, Elizabeth is haunted not by the bodies she left in her wake as an MI5 spy but by her beloved husband’s advancing dementia.

Sharp Edges

There’s nothing wrong with writing a brooding detective who’s battling their own demons. But if you want to get creative, you can create a little complexity for your protagonist by finding a balance of dark and light within them.

The titular character of the Chief Inspector Gamache series is known as humble, kind, and—get this—looks for the good in people. But that doesn’t make this a cozy mystery series (at least not according to Louise Penny). Gamache is still forced to confront the harrowing business of murder and the psychological darkness behind it.

Detective Character Development

A senior woman wearing an apron washes carrots in a kitchen sink.

Now that you know how to adapt your gumshoe to fit the mystery genre, what about basic character development? What should you be thinking about as you create your fictional detective?

Find Their Strengths

You always want to know what your main character is excellent at no matter what type of fiction you write. But in a mystery novel, your sleuth’s unique skill set is a big part of the fun.

What makes this character different not just from other investigators in your story, but from other detectives in the wide world of fiction? Can they always spot a lie? Are they an unsentimental observer? Do they have a Super Sniffer?

Find Their Weakness and Flaws

On the flip side, what shortcoming threatens to trip up your detective? Do they take each case too personally? Do they pass out at the sight of blood? Are they over-confident? Irresponsible? Do they shut people out, either in their personal life or the investigation?

How might your sleuth’s weakness place them in greater danger? How does their biggest flaw almost ruin the investigation?

Give Them Meaningful Motivation

Just like any other character in any other novel, your detective needs a solid reason for putting their sanity and safety on the line to solve this crime. So what is it?

Quick tip: motivation is almost always in the character’s backstory. Whether they endured trauma or idolized a detective parent as a child, there’s an emotionally compelling history pushing them to pursue this goal.

Set Them Apart With Quirks

Quirks are the small details that endear your detective to your readers.

Harry Bosch (Harry Bosch series) listens to jazz while reviewing clues. Joyce Meadowcroft (Thursday Murder Club series) leaps at any chance to include celebrities, shopping, or her daughter in an investigation. Darby Hart (A Murder at the End of the World) feels dead people compelling her to seek justice on their behalf. You know, quirky stuff.

Flesh Them Out Fully

Of course, as you likely guessed, this stuff is only the beginning. This person is the hero(ine) of your detective story, which means you’ll need a complete picture of who they are. For help on that, I recommend:

Embedding the Detective Into the Mystery

As you create your sleuth, keep in mind how they’ll fit into your larger mystery story. The most engaging detectives don’t just solve a puzzle. They’re consumed by a riddle that occupies their every thought and disrupts their entire life.

Ask yourself:

  • What is at stake for the detective in this story?
  • What are the consequences of pursuing this case? What do they risk or sacrifice?
  • What would they risk by not solving the crime?
  • When, why, and how does the case become personal for them?
  • How does their involvement make the investigation smoother? More complicated?

Key Relationships in a Detective Story

Two detectives stand outside an interrogation room holding coffees.

This article is all about the main character of your detective story. For tips on how to write an entire cast of mystery characters, click here. In the meantime, we’ll briefly explore how your side characters relate to your sleuth.


The detective/suspect relationship is always fun because it’s built on a rickety foundation of mutual distrust. Everybody’s side-eyeing everybody. Suspects often have secrets even if they didn’t commit the crime. Detectives have to be careful about how and when they reveal what they know. 

It’s a super tense relationship and I am here for it.


The sleuth/villain relationship is also fun because it can be anything.

Will the perpetrator turn out to be the detective’s childhood friend? The suspect they wrote off on page 47? When your hero(ine) realizes the killer’s identity, will they feel betrayed? Vindicated? Stupid?

It’s all up to you. You’re the writer. 

The one thing you (probably) don’t want to do is create palpable loathing between these two characters for the entire story. Too on-the-nose.

Colleagues or Sidekicks

Most fictional detectives have a little help, whether it’s a good friend to bounce ideas off of or their partner on the force. These characters can offer support or create friction. It’s up to you what the story needs.

Personal Relationships

Even in crime fiction when the investigation is everything, readers expect a glimpse of your detective’s personal life. As long as they’re peeking, you might as well give them a little conflict, too.

Who does your sleuth love most in the world? Where is there disconnect? How does their crime-solving obsession impact the people closest to them?


Not to be confused with a villain (which is a type of antagonist), an antagonist is anyone who gets in the protagonist’s way. This includes the chief who kicks your detective off the force, the hotel manager who tries to keep your sleuth away from the crime scene, and even the spouse who threatens to leave if your main character won’t give up the case.

How does the detective respond to these types of antagonism? Which antagonists have the power to make them feel small and which are just inconvenient obstacles?

Your Detective’s Arc

Finally, we need to talk about your detective’s character arc. This is the journey of growth a character goes through over the course of a story. Your sleuth might have:

  • A positive arc - They change for the better.
  • A negative arc - They change for the worse.
  • A flat arc - They don’t change at all.

A big positive or negative arc will always work best in a standalone detective story. If you plan to write a full mystery series, you don’t probably want your main character to transform drastically over the course of a single novel. Readers tend to get attached to series detectives just as they are, flaws and all.

That doesn’t mean they’re never interested in watching the protagonist grow. You might think in terms of a series-long character arc in which your gumshoe makes tiny steps forward (as well as the occasional step back) in each book.

Or go the Sherlock Holmes route and opt for a flat arc.

For help writing a compelling character arc, check out this article.

One Last Tip as You Craft an Intriguing Investigator…

Screenshot of a mystery cast in Dabble.

Let Dabble help! This all-in-one novel writing tool allows you to create customized character profiles complete with property lists, images, notes, and more. 

You can also use the famous Plot Grid to track your detective’s arc in a standalone novel or plan and write several books within a single project so you can stay on top of their series-long transformation.

To learn more about writing detective fiction with Dabble, check out this article and template.

Or just dive in and start exploring! You can snag a 14-day free trial by clicking this link. The trial gives you access to every one of Dabble’s features, and you don’t have to enter a credit card to get started.

Whether you write your detective story with this tool or opt for a different path, remember that Dabble is always here with free articles and a community of fellow writers. So don’t be afraid to start piecing together that mystery writing career. We’re with you as you step out into the puzzling unknown.

Abi Wurdeman

Abi Wurdeman is the author of Cross-Section of a Human Heart: A Memoir of Early Adulthood, as well as the novella, Holiday Gifts for Insufferable People. She also writes for film and television with her brother and writing partner, Phil Wurdeman. On occasion, Abi pretends to be a poet. One of her poems is (legally) stamped into a sidewalk in Santa Clarita, California. When she’s not writing, Abi is most likely hiking, reading, or texting her mother pictures of her houseplants to ask why they look like that.