The giant rats were once the favored pets and messengers of the God of the Underworld. They have been replaced by the crows in this respect and have been banished to the edges of the Dark Sea.
These rats possess a keen animal inteligence and are capable of mimicing speech. They were once able to swim short distances in the sea of the dead, and to facilitate their movement from island to island ancient stones were errected. Many of these stones are still in place.