I need a peanut gallery. I'm working on a story and am stuck at the beginning, I need to design a hero/heroine, but all I have to work with is the current opening phrase:

"What is it that lies in the dark conners of human hearts? Why do so many fear it? Why do so many succumb to it? What happens to those who embrace it?"

It would also help to have a base setting to the story. But, the real thing is those who fear the darkness, those who succumb to the darkness, and those who embrace the darkness. Those who fear it are also those who fight it, the basic good guys. Those who succumb to the darkness, the usual bad guys who claim to have embraced the darkness or call it their destiny. So, who are the ones who actually embrace the darkness and what happens to them?

I need a giant desert monster in a post apocolyptic Earth setting for the main hero to be introduced.