I always thought that THG was based off of Theseus and the Minotaur. I'll sum it up: It is described that teenagers (both boy and girl) were forced into the labrynth in Athens each year to try and kill the minotaur (head of bull, body of man). Theseus desides to slay the minotaur and end the killings with his girlfriend, Princess Ariadne. She advises him to use golden thread to show him how to get out of the maze after he slays it, which he does. The actual story is much longer, but I immediatly thought of THG and how the reaping system works. You can find out more by searching up the story.