A major core plot line revolves around the protagonist's inner story. To satisfy the inner plot line, the protagonist must undergo a deep and fulfilling transformation. Often this is accomplished by introducing the character at the Beginning of the story with a flaw that must be eventually overcome to achieve her ultimate story goal.
Following are a few examples of character flaws:
1. Always the victim and unable to take responsibility for actions
2. Control freak
3. Argumentative and short-tempered
4. Liar and a cheat
6. Always have to be right
7. Perfectionist and procrastinator
Character flaws in otherwise function individuals are often created in response to the character's back story. The back story is the moment when the protagonist loses her innocence. Because of what happens to the character in the back story, she now (in the front story) holds beliefs or exhibits actions that reflect a deep psychological issue that sabotages her from achieving her overall story goal.
The character flaw is introduced in the Beginning (1/4) of the story, deepened in the Middle (1/2) as the stakes rise and her internal flaw trips her up more and more often until she can no longer deny her part in her failure, an awareness which triggers her ultimate transformation at the End (1/4) of the story.