Believable characters exhibit character traits.
Giving the characters in your screenplay individual traits is a great way of diversifying them and making them feel more real and human. A trait is a small detail particular to one character; it could be something about their physical appearance, or about the way they think , or the way they speak, or any number of the particulars that make up an individual, but it has to be something special to one character.
A trait is not whether the character is good or evil, or what decisions they make. A trait is a scar, a potty mouth, an unerring passion for Twinkies.
Watch our video below to find out more about character traits: