In human form, Poseidon, Greek god of the sea, appears as a tall, muscular, and deeply tanned fortysomething man with black hair, a neat beard, and warm, sea-green eyes with deep laugh lines. He dresses casually in a Hawaiian shirt decorated with coconuts and parrots, Birkenstock sandals, and an old fisherman’s hat with lures and the words Neptune’s Lucky Fishing Hat. His temperament is relaxed, even joking at times, unless he is at war, when he channels his water-manipulating powers and fights with furious determination. When faced with a losing battle, his appearance changes to reflect the state of affairs—from young to old, dark-haired to gray, strong and upright to slumped and defeated. Turn the tables, however, and his appearance reverts to his former youthful vigor.

Poseidon is a caring, if distant, father to Percy Jackson. He helps if and when he can—sending hippocampi to carry Percy and his friends over the ocean, blasting the giants Otis and Ephialtes with water in the Athens Acropolis—and openly praises his son before the other gods, and visits Percy on his birthday. He claims Percy is his favorite child . . . not surprising, considering some of his other children are rather nasty characters, including the giant Antaeus, who tried to kill Percy.