Triton

Triton is a mythological Greek god, the messenger of the deep. He is the son of Poseidon, god of the sea, and Amphitrite, goddess of the sea, whose herald he is. He is usually represented as a merman, having the upper body of a human and the tail of a fish.

Like his father, he carried a trident. However, Triton's special attribute was a twisted conch shell, on which he blew like a trumpet to calm or raise the waves. Its sound was so terrible, that when loudly blown, it put the giants to flight, who imagined it to be the roar of a mighty wild beast. Triton dwelt with his parents in a golden palace in the depths of the sea

Triton was the father of Pallas and foster parent to the goddess Athena. Pallas was killed by Athena during a fight between the two goddesses. Triton is also sometimes cited as the father of Scylla by Lamia. Triton might be multiplied into a host of Tritones, daimones of the sea.

Triton also appeared in Roman myths and epics as the son of Neptune and Salacia. In the Aeneid, Misenus, the trumpeter of Aeneas, challenged Triton to a contest of trumpeting. The god flung him into the sea for his arrogance.

In The Last Olympian
He is described as have green skin, black hair, and two tails, like a merman. He is somewhat cold and arrogant to Percy, talking down to him and acting as if his half-brother was lazy for not appearing sooner (this is after Percy jumped off the now blown up Princess Andromeda), though is respectful to Tyson. Triton makes fun of Percy, smiling at one of his comments. He is seen only briefly, however, so his actual attitude in general is unknown.He also seems to be proud of being Poseidon's son( saying "Your son and heir!").