Last week I shared the story of a shooting near our house. If you haven’t read that post, hop on back and read it first, then move on to this one.

When the dust settles after a tragedy in which the human will was involved–as opposed to a natural disaster–the very first question we ask ourselves is Why? What drove the villains of innumerable wars and genocides and school shootings and kidnappings and murders to commit such heinous acts? We want a reason, even if it’s an inadequate one, for the crime. And when we don’t get it, it makes the tragedy more frightening. Whatever the reason, it is so much easier to process and understand if it isn’t random.

When it comes to storytelling, motivation is key to understanding characters, accepting the plot, and fully immersing ourselves in the story. If there’s no clear reason for an action, the reader will be continually on the lookout for it. Now, if we want to make unclear motivation part of the tension for a while, that’s fine. But if we never manage to explain to a reader why a character, say, betrays his brother or cries when he sees a field of ripe wheat or sabotages his best friend, we’re betraying their trust in us as storytellers.

In high school I was in a number of plays and musicals, and beyond the very obvious difference of one having musical numbers and one not, I noticed a very pronounced difference in stage direction. In a play, if I stood up and walked to another spot in the “room” for no apparent reason, the director would call me on it. I needed to have a reason to change my position beyond me just feeling like the audience would be bored if I sat the whole time I was delivering these lines. In fact, it was so ingrained in me that it has affected my enjoyment of other productions! A common problem when memorizing lines and movements for a play is to answer the question What’s my motivation? because, of course, as an actor you are given lines and stage direction in a non-organic matter. To you, they did not arise naturally. Someone else wrote them out and you have been tasked with performing.

In contrast, the director of the musicals needed little reason for movement beyond the need to get people into the proper spots to start the next dance number. If you’re manipulating events in your manuscript just so you can get to the next scene that you planned, step back a moment and examine each character’s motivation. Would someone really act that way, say that line? Why? What would drive them to do that?

Using my example of the recent deadly shooting from the post on tension, after the shooter was taken into custody our questions changed from Who? and Where? to Why? Why the pharmacist? Was the shooter attempting to steal drugs? Was he under the influence of drugs? Why his neighbor? Had they been at odds?

The day after the shooting I was attempting to organize my desk (because deeper thought eluded me, preoccupied as I was with the events of the day before). This process involved going through a stack of items to be read and filed, including several issues of The New Yorker. I was flipping through them for articles and stories and comics I wanted to rip out and keep when I ran across an article about Adam Lanza’s father. I didn’t want to read about Sandy Hook, especially after the experience of my son’s school being on lockdown. But for some reason I began to read anyway. The article essentially attempted to explain what created a killer and a scenario like Sandy Hook. It talked about Adam Lanza’s childhood and teen years, his slow descent into a mental prison, the enabling actions of his mother, the frustration and despair of his father, everything, it seemed, except personal motivation. And that’s because that’s all we’re left with when a mass murderer kills himself and leaves no explanation. We’re left to grasp at wisps of clues and will never know the full truth.

But as writers, we must know why our characters are behaving the way they are, doing the things they’re doing, saying the things they’re saying. Read through each scene of your work in progress. Are the motivations of your characters clear? You don’t have to tell the reader outright why someone did something. You just have to make it easy enough for them to figure out on their own.

In my current manuscript, I wasn’t happy with one aspect of the ending. A young character committed a heinous act because I needed another character to suffer the consequences of their actions. The only problem was, I didn’t give this young character enough motivation. I tried adding a bit here and there, but what he did was so awful, my sprinklings of motivation were not enough, and I knew it. Rather than change the ending so that my other character didn’t suffer the consequences of her actions, I simply switched the young man’s target and made the consequences to the other character accidental. Problem solved.

Not everything needs an explanation of course. You don’t need to tell us why your protagonist rescued a dog from a shelter. It’s a pretty common thing humans do because most people like pets. However, you might have a reason for your protagonist choosing a large and imposing dog rather than a little yippy one. Or choosing a dog rather than a cat. That may factor into the plot or it may simply tell a reader something about the character that’s important.

Remember, if your character moves stage left, there had better be a reason for it or the spell you are trying to cast will be broken. Your audience will remember that they’re reading a book. And that’s exactly what we don’t want them to do.