Motives matter in life—and even more in mystery fiction. Creating a credible motive for a character’s actions is at the heart of a good story. It’s not enough to say “he was crazy” or “she was overcome by passion”—even the wildest backstory needs a core of sincerity and reason. Real life can be, and sometimes is, completely irrational, but fiction requires the motives and actions of characters to make sense.
In a good mystery, motive is an essential element of the crime. Although a reasonable motive is not required to prosecute a crime in court, a story that hangs together, a motive that justifies the character’s actions—at least on some elementary level—makes the story compelling. When mystery writers fail to provide a motive, it’s hard to make the reader care.
Rotten childhoods, blackmail-worthy secrets, greed and lust crop up all over mysteries. Love—unrequited, mistaken, misguided, twisted or otherwise problematic—is an even more powerful source of backstory motives. A soured romance leading to an obsession is a popular cliché in mystery fiction. I just read yet another romantic suspense novel that relied on that formulaic motive.
Agatha Christie was famous for exploiting the power of secrets in her many novels and short stories. Her rational people kill to protect their secrets and her blackmailers risk murderous revenge in classic stories.
Coming up with original motives is a huge challenge and that may be why storytellers return to familiar territory when it comes to WHY even if the WHO and HOW are completely new. Drawing from true crime only goes so far because in real life people don’t always have motives that justify their actions.
Mark Twain wrote, “Truth is stranger than fiction, but it is because Fiction is obliged to stick to possibilities; Truth isn’t.”