Tip #114: Behind the flaw

Perhaps...

your character has a major flaw that came about as a defense mechanism to protect himself from his deepest fear, but he is also driven by a need that causes him to make plans (plot!) to achieve his goal

http://www.routinesforwriters.com/2011/04/20/character-builds-plot-builds-character/

i.e. That fear you're going to make your character face? How does it affect his/her behaviour?  The conflict between need and fear is compelling: we've all been there.