Echidna in The Lightning Thief

Echidna

We don't hear much about Echidna in this story, except that she is Chimera's mommy. She disguises herself as a human and rides the elevator with Percy, Grover, and Annabeth to the observation deck of the Gateway Arch. There, she unleashes her pet Chihuahua on Percy. The Chihuahua morphs into Chimera.