Luke Castellan is a character from the Percy Jackson & the Olympians series by Rick Riordan. He is a demigod, the son of Hermes, the Greek god of travelers and thieves. Luke is initially introduced as a charismatic and skilled warrior at Camp Half-Blood, a sanctuary for demigods. As the story progresses, Luke's character becomes more complex. He struggles with feelings of betrayal and ultimately aligns himself with Cronus, the Titan lord, seeking revenge against the gods. His journey explores themes of loyalty, ambition, and the consequences of choices in the world of mythology.