Everyone wants characters you can believe in, ones that you can see existing both in your story and real life. It doesn’t matter if it is horror, fantasy, or sci-fi, or if all your characters are elves or some new alien race. This is true for the readers seeking characters to invest in, hate, love, or follow. This is even more true for the writers who are working on their own piece of fiction. It is a selfish desire to be entertained and to have your work cared about. It is that desire that we see one of the first keys to making characters believable, you do that by making them selfish.
The characters need to be selfish. Not entirely, but each character needs to have their own goals and dreams that they are willing to put above everyone else’s. Their goals can align, but they have to be different. They can be for the greater good, the greater bad, or just to fulfill their personal desires. Knowing and showing that the characters want things, and not only to serve the World, Main Character, Plot, or Mcguffin. Each should have a purpose that his at some way selfish and personal.
People have selfish little desires. When you can see the characters having those same things and acting on them. You can believe in that. They may give into those selfish desires, they may fight them for some noble cause. Do they want power, love, security? Show that through little actions or goals. It’s the little things, comments, movements, that show that the current situation or even the main problem are not the only priority to those living in the written word. The thing is you have to give that feeling and don’t need to be specific.
Not being specific is another thing that helps build believable characters. The author has a vision of their character in their mind, and no reader will see the characters exactly the same way. Humans don’t follow the dictionary with definitions, so even if you write as clearly as you can, the readers might have a different interpretation of the words you use. Not to fret, this difference is vital. You want your readers to be able to fill in the blanks. It puts them more into the story, and as they craft the characters in their own minds, they can’t help but make them more believable.
In John Scalzi’s Lock-In, he doesn’t even mention the gender of the main character and actively avoids such references allowing the reader to form their own image of who is controlling the droid body. I’ve taken the same approach in some of my books. In the Crafting of Chess, I never mention the Main Character’s race, eye, or hair color. In some ways, that is because I want the reader to imagine how they view the character, but I also want them to be able to insert themselves into the first person perspective better.
This approach can go for all characters, but it is tricky because you still want some way to be able to make their mannerisms and voices different. But you don’t have to give them an up and down head to toe description. Every time you let the readers build the characters in their own minds, you make them more believable, more relatable. Allowing each person to have their personal relationship with the characters.
It’s not just seeing characters desires and letting people build them up in their own mind. It’s how we judge the characters interactions with people and objects that help make them real. It’s their relationships and how they interact with each other or animals or even inanimate objects that provide another connection. Showing who, what and how the characters relate to each other or even off page people opens up a window that readers can follow and believe in. It can also make it so much more dramatic when you break those connections.
What is Office Space’s Milton without his Red Stapler? How does Carrie feel about Margaret White? How do any of the characters treat each other? Sure it is convenient to have your protagonist be an orphan without those connections. Classic dead parents and no friends trope that lets us feel sympathy for the main character. What would Batman be without his relationship to Alfred? How the characters treat things tells us more than their words and even actions can. It is something we need to see to believe.
When crafting those believable characters, we need to combine these tools and traits for the reader to feel and discover. They need to see the selfish desires, to see what kind of person they are through their relationships, to give enough leeway for readers to put their own vision into the characters. When you write them, ask what those characters want, ask who or what they have emotions or responsibility towards, ask how much is really needed to present the creation and what can be filled in by the reader. That is how you craft believable characters.

Kit Falbo writes science fiction and fantasy. He is the author of The Crafting of Chess, a near future VR LitRPG, And Intelligence Block, a pulpy science fiction adventure. He lives in the pacific northwest and has a degree in psychology. He loves gaming, writing, and his family.
Lilyn G is the founder of Sci-Fi & Scary, and leader of the Coolthulhu Crew. She does book and film reviews for both genres the site focuses on. Her tastes run towards creature features, hard science fiction, and lots and lots of action. She also has a soft spot for middle-grade fiction that rears its head frequently.
Though no longer involved with Ladies of Horror Fiction due to other responsibilities and a too-full plate, she was one of the original 4 co-founders.
Feel free to chat her up on Twitter as long as you aren’t hitting her up to review your book.