Develop fictional characters by considering their ambitions, secrets, contradictions and vulnerabilities. Drawing inspiration from real life individuals can also help fiction writers develop characters, but it is not necessary to be precisely true to life.
Almost all characters, whether good or evil, are driven by an underlying motivation that spurs them to action in the story. They may also have a secret that defines their character and creates conflict, such as a trait, flaw or hidden part of their history. A good character may have facets that contradict one another, such as a person who is shy but also cruel. Finally, developed characters have some sort of vulnerability that makes them relatable and adds complexity to a story. These traits are often intrinsically related, such as with a character whose secret is her motivation or a character whose vulnerability is part of his contradiction.
Many authors take at least part of the inspiration for their characters from people in real life. While it’s not necessary to perfectly translate someone’s personality into fiction, a writer often takes aspects of someone she knows in order to better develop an existing character. Considering people who elicit strong emotions, such as fear, admiration, love or anger, is often a good first step when considering sources of real life inspiration for a fictional character.