Which brings me back to characterization. Direct characterization is when the author TELLS the audience what the personality of the character is. Indirect characterization is when the author SHOWS attributes that reveal the personality of the character. Attributes that perhaps even the main character is unaware of. When writing the backstory of a round character, I use the S.T.E.A.L. Wheel. It's a practical little graphic organizer for any writer.
S.T.E.A.L. is the acronym for Speech, Thoughts, Effect on others, Action, and Looks. Specifically:
Speech: What does the character say? How does the character speak? What is revealed through the dialogue?
Thoughts/Emotions: What is divulged through the character’s intimate thoughts? How does the character feel about the people and events unfolding around them?
Effect on Others: How does the character cause others to react? What happens to others as a result of the character's reactions to things?
Actions: What does the character do? How does the character behave? What are the consequences of their reactions?
Looks: What does the character look like head-to-toe? How does the character dress? What are distinguishing characteristics?
I love the S.T.E.A.L. Wheel. I use it when teaching and writing indirect characterization - because KNOWING your character is essential to WRITING character.