Annabeth Chase, a demigod daughter of Athena is Percy's girlfriend. She is very smart and ends up taking a liking to Tyson even thought she has a a bad experience with Cyclops.....
Tyson is a Cyclops with one eye but the Mist makes it seem like 2. He makes weapopns like a watch-shield for Percy for the war against Kronos. He and Percy are brothers.
Luke, a demigod son of Hermes who is Kronos' #1 servant.
Grover, a satyr (a half-human half-goat.) He wears fake feet to hide his hooves.
Percy Jackson is a demigod of one of the Big Three (Posideon) and wasn't supposed to be born he is the main character and everything is told from his perspective. Riptide, his pen sword has helped keep him alive
Clarisse La Rue. A demigod daughter of Ares. She and Percy hate each other and she attempted to give him a swrily. She is a bully.