If you’re looking for a way to flesh out your characters, check out this site: Character Flaws: The Seven Chief Features of Ego.
What I find fascinating is how each flaw is exhibited in people, and why.
For example, The Martyr Complex. Someone with this flaw is convinced that s/he’s persecuted, and believes that s/he’s been robbed of choice. This can be because of childhood abuse, or it can be a coping mechanism a person developed under any number of circumstances. What’s fascinating is that the flaw has a polar opposite; in this case, it’s selflessness. What I’m playing with is how both poles live in us (and our characters).
My main character’s chief flaw is Self-Destruction. She’s homeless and alcoholic, and she fiercely guards both of these things because she feels like she has control over them. The opposite pole of self-destruction is sacrifice; this ties in neatly with martyrdom, which is her shadow because she is unaware of it.
I find it’s much easier to craft characters by starting with their flaws. Flawed people are more interesting, and we expect them to let us down, so hints of nobility surprise us. I think those hints give us hope for our own selves, that there might be something redeeming in our own persons that makes us lovable.