Once upon a time:

The world was taken over by two leaders. The leaders were enemies. One, the Silent Leader. They see all, but refuse to speak their mind. The other, the Loud Leader. They see nothing, and speak their minds all the time. They refuse to not be heard.

They were at war, you either kill or be killed now as their was a sickness spreading, turning people against each other, eating each other. Like zombies.