The relationship between the victim and the villain is the basis for the build to the reveal in a traditional mystery. Your sleuth must discover the victim and their world before unraveling the threads that lead to uncovering the villain.
Your understanding of the two characters and their relationship is pivotal to constructing a sustainable mystery. To find the villain, your detective must understand the victim. That understanding builds and brings your detective closer to the villain.
When you understand each character, you can build relationships and antagonisms that lead toward the conclusion. Without a strong background for each of these main characters, your mystery will fall flat. Your reader may guess the villain before the conclusion. The victim won’t seem worthy of killing. Your sleuth won’t be challenged.
The victim is the rai·son d’ê·tre of the mystery. Without the victim, your sleuth would have nothing to do—no clues to find, no suspects to interview, no puzzle to solve. There would be no mystery.
As a writer, you need to build a strong character background for your victim. Even though they have no speaking part and appear as a corpse, the victim is the foundation of the mystery. Suspects derive from their circle of friends and enemies. You sleuth learns about their quirks, likes and dislikes, and personality traits by interviewing the suspects.
The first half of the novel is spent discovering the victim’s world. The reader learns through clues and suspects about the victim’s circumstances and their relation to other people, including the villain, and the world they inhabit.
The reader follows your sleuth’s investigation. Along with the sleuth, they form opinions about the victim; a despicable human, a seemingly virtuous soul, a likeable scoundrel. And, like the sleuth, they try to guess why the victim was killed and who did it.
So, your victim is more than just a dead body. Something they did triggered a murder, and you, the writer, need to know why.
A challenge for mystery writers is creating an antagonist worthy of your sleuth while keeping them hidden at the same time. In order to accomplish this and keep your reader guessing until the end, you need to create a full, deep character background.
To make the murder believable, you need to tie your villain’s motivations to the victim’s personality. Until you know the victim’s personality, you will lack a true motivation for the villain. It’s backstory gone wild except you can only dribble tiny pieces of this backstory into the novel.
Until you know the motivations and methods of the villain, you won’t be able to keep them a secret. The villain works behind the scenes through most of your novel. But, you need to know the why and how in order to hide the villain in plain sight.
At the same time, you need to know how the villain puts pressure on the sleuth, leads them down false trails, and hides their antagonism to the sleuth.
The Relationship is The Big Clue
What you know as the writer and what you want to hide from your reader is that the relationship between the victim and the villain is the big clue. The relationship is the mystery’s background.
Think of your background as data collection. Then drip various pieces of information about the relationship throughout the story. Use those bits of data the same way you add other clues to your mystery.
You’ll find as you develop your storyline and while you are writing that your full knowledge will help you create unique and believable situations in your mystery.