Zethes

Zethes is a son of Boreas and Oreythyia, and the brother of Calais. He was a demigod until his father offered him and his brother Calais immortality. His sister is the goddess of snow, Khione. He doesn't get along with her nearly as well as he gets along with his brother Calais. He traveled to retrieve The Golden Fleece with the original Jason, on the original Argo. He was said to be the fastest demigod alive.

The Lost Hero
Leo describes Zethes as a teen who looks like a "love god from one of his mom's 1980's" rock album covers. He has a bad case of acne. He and his bother Cal allow Leo, Piper, and Jason enter into Boreas' home.

Zethes is obvious in his attempts to impress Piper, often commenting that she is very pretty, and when she loses the blessing of Aphrodite, he offers her some of his own beauty products, which she refuses.

Zethes and his sister Khione both want the demigods turned into ice statues (so Khione could keep Jason, and Zethes could keep Piper) but their father Boreas refuses, wishing to let them go. As they leave, Zethes and Cal warn them to be careful, especially when Jason insults Khione, because she never forgets insults.