the beautiful three-headed hound, with a mane of live serpents n dragon's tail, was the watchdog of Hades, a realm of dead. it permitted new spirits to enter, but allowed none to leave or returned to the human world. Cerberus (offspring of Typhon n Echidna) was said to be flesh-eating, fierce enough that the gods fear him. Hercules once fetched Cerberus from the underworld. besides him, Orpheus was the only other person attempted to go against Cerberus.