Hephaestus is the god of fire and blacksmiths. He never appears in the novel in person, but Percy has to deal with him regardless—Hephaestus’s wife, Aphrodite, is in a relationship with Ares, and Hephaestus sets up a trap at a Denver amusement park designed to embarrass the lovers on Mount Olympus television. Thanks to Ares’s trick on Percy, Percy and Annabeth end up walking into and dealing with the trap.