Creating Convincing Characters
Characters (like people) primarily define themselves by what they do, not by what they say. Action defines character.
Convincing characters have a belief system that drives their actions. Their belief system shapes how they perceive their world, how they perceive themselves and others. In order for your characters to act with conviction, and to act convincingly they must act according to their belief systems.
Your characters will have varying degrees of self awareness about their beliefs – some will be self aware (but never completely so), and others will be in various stages of denial. Also, no two characters (just as no two people) will share the same view of the facts.
In most cases your character’s belief systems will change during the course of your story as your character develops and grows in response to outside forces. Or, if you have a character who is incapable of self awareness, their belief systems will likely remain the same, as the people and circumstances around them change profoundly, precisely because your character is unable to change their belief system even in the face of compelling evidence that it is not viable.
Your characters’ belief systems can be conveyed through dialogue, gestures, quirks, idiosyncrasies, habits, and actions.
Writing Prompt: create a scene with two characters doing laundry together, each with their own belief system about laundry and life.