One of the things I've learned in revisions and through writing and rewriting is that it is essential to find the ultimate mood of a character. Mood defines a person. By this, I mean that underlying attitude about the world, the filters the character sees the world through. This is different for us all. Consider the way people react differently to being late, being lost, or when given an unexpected twist. I despise being late so much that I have actually set the clocks in my house twenty minutes fast so I always show up early to wherever I'm going. But I actually like being lost--whenever I move somewhere new, I drive around for hours until I get thoroughly lost, then try to find my way home by the most random routes I can find. This is totally different from my husband: he likes precise time, and likes showing up at the right time, not early. He wants to know the shortest distance, not the most convoluted one.
For characters, it's often much easier to present this simpler. What is one core attitude the character has? For my most recent work, I'd say that Amy's core is based on family; for my other character Elder, his core is based on responsibility. So, Amy's actions are based on a desire to protect or be with her family; Elder's is based on a desire to be a responsible leader.
In the new project I'm working on, it's even baser than that. Both main character's fundamental desire is simply to exist within their society. They are working up to shout their barbaric yawp to the world.
And since I mentioned the barbaric yawp, I can't help but include this: