Don't fall into the "black or white" trap!
It's easy even for experienced novelists to fall back into stereotypes when it comes to heroes and villains.
I've asked more than one war hero why they believed they were motivated to act courageously under fire? Two of them answered more or less this way: "I was terrified I would be a coward so I just ran into the fire!"
Remind yourself that every hero has flaws and every villain has tried to do the right thing--at least once in her life.
1) List three good things your villain has aimed to do. If she failed, why? And was that a pivotal moment in her world view? If she succeeded, how does she look back on her deeds?
2) List three bad things your hero aimed to do. If she succeeded, what happened? How does she feel about those bad things now? Does she keep them secret or does she share her flaws with someone or with everyone?