Iris, the owner of the staff.
Mercedes is a staff used by Iris.
The Senior Year Adventures[]
The Chalice of the Gods[]
When searching for Ganymede's missing chalice, Percy Jackson, Annabeth Chase, Grover Underwood seek out Iris for information about the chalice. The Rainbow Goddess agrees to give them the information they want if they clean her staff in the River Elisson in exchange. With help from Eudora, Percy locates the river along the Saw Mill River in Yonkers and he takes his friends to the river. After finding Horned Serpents, Grover distracts them as the demigods clean the staff. However the river god Elisson finds them and attempts to drown Percy, but the son of Poseidon easily overpowers Ellison, scaring the god. Annaberh comforts Ellison as the god agrees to let them leave. Percy distracts the serpents as the daughter of Athena helps a tired Grover. Once Percy is cornered, he wishes to be with Annabeth and Grover and the staff takes him to his friends.
A few days later, Percy and Annabeth return the cleaned staff and Iris gives them vague information on a god named Gary.