Alongside the ruling Groan family there is a large population within the castle who service its daily needs. Although the "Castles", as they are known (to distinguish them from the Bright Carvers), are all commoners, they are nevertheless highly socially stratified, from the socially respectable Dr. Prunesquallor and the Professors to the lowly Grey Scrubbers, whose sole job is to clean the walls of the kitchen. However lowly the position of the "Castles" may be, they consider themselves to be far superior to the Bright Carvers who live outside the castle walls.