List of characters in the Camp Half-Blood series
Echidna - Part woman, part snake. She is the wife of Typhon and the mother of Cerberus, Chimera, Hydra, Nemean Lion, and Ladon as well as several others not in the series. She is first seen as an old lady that owned the chihuahua that was actually Chimera in disguise. She assisted Chimera in fighting Percy at the top of the St. Louis Arch. She and Chimera disappeared after Percy dove into the water.