I have Tyrian or Jupiter who might hit it off with Riordan as they both appreciate sass and crudeness. And both will probably find him terribly good looking ;D
Tyrian has a saber-toothed snow leopard companion named Zahir, a black-footed gray langur named Tashi and a striped skunk companion he insists on calling Righty even though her name is Daisy. Assume all are nearby if not mentioned.