Prudence is a young girl (referred to as a "child") living in an unknown world. Her father is Chrestomanci's agent Kathusa and they have a dog called Towser. It is unspecified who her mother is or if she is still alive.
The only description of Prudence is that she has "reddish hair and a slobbery sleepy face".
Prudence is bossy. Towser usually backs her up. She is also spoiled.