on Writing Forward:
In order to develop a truly compelling character, it’s critical for an author to know what the character wants and what’s standing in the character’s way.
If you want to create a complex character, identify an external goal and an internal struggle for the character, and make sure the goal and struggle are at odds with each other. For example, in The Hunger Games, Katniss Everdeen struggles internally because she doesn’t want to hurt anyone; however, to survive the Hunger Games, she needs to kill her opponents—survival is her external goal. This pits her personal values (don’t harm others) against her external goal (survive).
When a story demands that a character challenge or reevaluate their internal goals and values, things get interesting. This is a surefire recipe for some much-needed conflict.