All you have to do is take a quick look at any Tumblr account and you’ll see how influential a character can be. Characters become your friends, your mentors, your inspiration for trying something you never thought of before. They can feel closer to you, at times, than your own family.
As a writer, you never know which of your creations will click with your readers. All you can do is give each character a whole life. Even if the plot doesn’t allow for you to divulge all the details, you need to know them. It’s that in-depth understanding that will come across in every move your character makes, every line of dialogue, and how they influence the plot.
So, go through your first draft and list out your characters—describe what they look like, know the key events in their past, work out who their family and friends are, even their health. What secrets are they hiding? What do they desperately want? What scares them? And, most importantly, how did they get to be in this story? Once you have those answers, you have the beginning’s of your story’s canon. And the more familiar you are with your canon—the stronger your grasp on your characters and their world—the better your story will be.
Now go through your draft again and make sure your characters’ words and actions reflect who they are.
Giving your characters those dimensions will prevent them from being flat, a cardboard cutout that you’re moving around to make your plot work out—someone the audience will forget. Think of your last plane, train or bus trip. When was the last time you saw someone generic, that didn’t have something interesting about them? It rarely happens. Everyone always has a little something of their personality peeking through. The woman in a business suit carrying a Hello Kitty lunchbox… or the little boy in a school uniform and faded, oversized army jacket. Everyone has something different and unique about them; so should your characters. Make them shine with individuality. Make them as real as the people you travel to work and/or school with. You can do this with dialogue that reflects their quick thinking and their worldview, the way they dress, the choices they make, etc.
A quick, and possibly slightly controversial, note about your main character: While it’s okay to have them exist in a story that they simply witness and report on… let’s be honest, the best stories have a protagonist that influences events, that drives the plot, even if it’s just some of the time. It’s even better if all of your characters impact the direction of the story.
Which brings us to Raiders of the Lost Ark. It’s a great movie. A perfect movie. But, as Amy in The Big Bang Theory pointed out, Indiana Jones doesn’t seem to influence any of the events as they unfold. The story, as she describes it, would pretty much have been the same had Indy not been there. Now, this has been proven to not be the case—there are multiple ways that Indy influences what happens, but the point is that you don’t want the fans of your story to feel like Sheldon while he’s listening to Amy deconstruct one of his favorite movies.
It’s not true about Raiders; don’t let it be true about your story.
Give your characters responsibility and agency, a past, insecurities and hope. Give them life.
In turn, they’ll give your story a life of its own.