Student who witnesses the strange events during the dodgeball game.

Now thirteen years old and still head counselor of Athena cabin. Becomes increasingly worried about...

School lunch staff who serve food to students including Percy and Tyson.

Student who joins in bullying Tyson but runs when the Laistrygonians attack.

Vampire-like monsters disguised as cheerleaders at Meriwether Prep. Have bronze legs and donkey...

Discovered through Percy's dreams to be trapped and in danger. Sends empathic distress signals to...

School custodian who cleans up after the supernatural incidents at Meriwether Prep.

Fellow student at Meriwether Prep who tries to be friendly with Tyson.

Student library assistant at Meriwether Prep who helps Percy with research.

A bully at Meriwether Prep who picks on Percy and Tyson. Represents the typical school antagonist.

English teacher at Meriwether Prep who assigns Percy difficult reading assignments.

Percy's PE teacher at Meriwether Prep who supervises the fateful dodgeball game.

Math teacher at Meriwether Prep who notices Percy's attention problems.

Plagued by nightmares about Grover being in danger. His connection to Grover through empathy link...

Principal of Meriwether College Prep who deals with Percy's disciplinary issues and unusual...

Medical staff member who tends to injuries from bullying and the unusual incidents.

A large, homeless boy who befriends Percy at Meriwether Prep. Other kids pick on him for being...

Son of Apollo who teaches archery skills to campers at the shooting range.

Children of Ares led by Clarisse, known for their aggressive nature and combat skills.

Daughter of Athena who runs the arts and crafts activities at camp.

Goddess of wisdom and warfare, mother to Annabeth and the Athena cabin children.

Satyr who prepares meals for the camp, works in the dining pavilion.

Winged cleaning creatures that enforce curfew and clean up after campers.

Daughter of Athena who maintains the camp's collection of books and scrolls.

Son of Apollo who runs the camp infirmary and treats injured campers.

Various nature spirits living at Camp Half-Blood, including tree nymphs and water nymphs.

Half-goat nature spirits who serve as searchers and protectors, like Grover.

Son of Poseidon (distant relation) who teaches water activities at the lake.

One of the twin sons of Dionysus, co-head counselor of Cabin Twelve with his brother.

Head counselor of Hephaestus cabin, skilled in forging and metalwork. Creates weapons and tools for...

Still head counselor of Ares cabin and maintains her rivalry with Percy. Continues to be aggressive...

One of the Stoll brothers from Hermes cabin, known for pranks and mischief around camp.

Daughter of Aphrodite known for her fashion sense and sometimes mean personality.

Long-time camper, daughter of Athena, helps train new campers in strategy.

Various children of Hermes and unclaimed campers living in the overcrowded Cabin Eleven.

Son of Hephaestus who works in the forges alongside Beckendorf.

Veteran camper, son of Ares, follows Clarisse's lead in cabin activities.

Head counselor of Demeter cabin, skilled with plants and agriculture. Often at odds with the Stoll...

Head counselor of Apollo cabin, skilled archer and healer who leads his siblings in camp activities.

New camper this summer, daughter of Demeter, still learning about camp life.

Son of Athena and Annabeth's second-in-command in Cabin Six. Intelligent and strategic.

New camper who arrived just before Percy, son of Hermes.

Son of Apollo known for his archery skills and competitive nature in camp games.

Son of Aphrodite in Silena's cabin, interested in beauty and camp social dynamics.

The other twin son of Dionysus, shares head counselor duties with Castor.

Daughter of Ares who supervises the lava rock climbing wall.

Young new camper, daughter of Apollo, talented with archery.

Head counselor of Aphrodite cabin, popular and beautiful camper known for her romantic advice.

Son of Demeter who cares for the camp's pegasi and other magical creatures.

Various campers who work in the camp's strawberry fields as part of their duties.

Son of Ares who teaches sword combat techniques to campers.

The other Stoll brother from Hermes cabin, partner in pranks with Connor.

Son of Apollo with exceptional healing abilities, works in the camp infirmary.