Percy Jackson is the son of Poseidon and Sally Jackson from New York. When the novel begins, Percy has no memory of who he is, only the vague sense that he has a girlfriend named Annabeth. Percy has spent several weeks with the wolf, Luna, and her pack, perfecting his fighting skills. He knows he is not a normal mortal, but he knows little else about himself. Luna sent him to the San Francisco Bay area for reasons he doesn’t understand. Once he arrives at Camp Jupiter, he understands that he is a demigod, and the camp is a place where other demigods train to be warriors. It is familiar to Percy, and he feels that he has been to a similar camp elsewhere.

Percy shows his abilities as a warrior at once as he fights two gorgons that refuse to stay dead. When he arrives outside Camp Jupiter, he is given the option of escaping to the sea and a life of solitude or staying at the camp and risking pain and misery. Percy shows his strength of character and his keen sense of right and wrong by continuing into the camp. As the story progresses, he continues to show his strength by refusing to stay put as his friends ask of him in a dream and takes on a seemingly impossible quest for a group of people he barely knows.