In comparison to Castor, Pollux is described as: "The other head was cuddly and cute, with a weak jaw, scanty fur, and sing-song voice." He is illustrated with white fur and blue eyes. When he is not sharing his body with Castor, he is seen with the bodies of smaller animals like goats.
Pollux is described as weak-willed and cowardly, and this is shown, for example, in how Castor takes their shared body for himself, meaning Pollux has to use makeshift bodies, such as deer. It's also shown how Pollux remained in the faculty of The School for Girls and The School for Evil, despite being neither, by sucking up to the respective leaders to keep himself safe.
Role at the School for Good
At the School for Good, Pollux teaches Princess Etiquette, an all girls class that teaches the Evergirls manners and how to behave in their fairy tales. He also teaches dancing to the Evers when the Snow Ball is near. He stays at the School for Girls and the School for New Evil, but is ultimately kicked out of the School for Good by Dean Dovey, and ends up teaching Agatha to dance in Camelot.