Nereus

Nereus is the old man of the sea and knows everything. Not much is known about his past. If captured, he will allow his captor to ask him one question. He can shape-shift into practically everything, including inanimate objects (though in his appearances in the series he only becomes aquatic animals such as a seal, an electric eel, and a killer whale). Nereus is sometimes known as Proteus.

Appearance
Nereus is described as looking like Santa Claus' evil twin, fat and having a white beard that turned kind of yellow. Nerues was wearing pajamas and a fuzzy bathrobe. He is also described as having a bad smell, like hot seaweed, dead fish and brine. Percy said that "If the ocean had an ugly side, this guy [Nereus]was it.

The Titan's Curse
Following advice from Apollo, Percy Jackson found Nereus at the beaches in San Francisco, California, and fought him through the water, as the only way to get a question out of Nereus is to hold on to him no matter whatever happens. During the fight, Nereus shape-shifted into different types of animals to shake off Percy's grasp. However, his tossing and shape-shifting didn't work well because Percy held onto him all the way through. Nereus was obviously tired of this way of life and just wants to be left alone. However, Percy tricked Nereus into jumping into the water with him holding on, making Percy stronger and overpowering him. Nereus was confused as to why Percy didn't drown at all, and Percy revealed that he was a son of Poseidon, much to Nereus' dismay. He eventually answered the heroes' question: Where the monster that Artemis, goddess of the moon and the hunting, was searching for was. Nereus simply pointed at the Ophiotaurus and escapes Percy's grasps and getting away through slipping through Percy's grip.

Children

 * With the Oceanid Doris:
 * Delphin
 * Glaucus
 * The Nereids - Thetis, Psamathe, Galatea, Ploto, Thoe, Sao and Others

Abilities

 * Able to change shape into aquatic animals (in The Titan's Curse he changed into a seal, killer whale, eel and goldfish while fighting Percy Jackson)