If your hero and villain switched places, how would they each react? How would the communities and people around them react?
What if your hero and villain were raised in the other’s place? If your villain had been raised with your hero’s background, would he/she still grow to be your story’s villain? What of your hero being raised how your villain had?
What would win out, nature or nurture? Would your character’s background, how he/she was raised, give way to their personality in the future, or are they slated for roles and personality?