Crataeis first appears in the Odyssey, the epic poem by Homer written in the eighth century BCE, where she is named simply as the mother of Scylla, the monster who dwelled in a cave on a rocky cliff in a narrow strait. When Odysseus and his crew were sailing home from Troy, they came to the passage where Scylla waited on one side and Charybdis, the whirlpool, on the other. Circe, the witch-goddess who lived on the island of Aeaea, had warned Odysseus of what lay ahead. She told him that Scylla was not a mortal creature but a deathless monster, savage and not to be fought, and that the best course was to row past her as fast as he could. But she gave him one more piece of advice: he should invoke Crataeis, for she was Scylla's mother, and it was she who had borne the monster to plague mankind. If Odysseus called upon her, Crataeis would hold her daughter back from darting out a second time. Odysseus followed this counsel, and though Scylla still snatched six of his best men from the deck of his ship, she did not strike again.

The name Crataeis means "Of the Rocks" or "Mighty One," and it speaks to her nature as a goddess of the dangerous coasts and submerged reefs that have claimed countless ships. In the ancient world, the Strait of Messina, which separates the island of Sicily from the toe of Italy, was notorious for its treacherous currents and rocky shores. Sailors who passed too close to the Italian side risked being snatched by Scylla, while those who hugged the Sicilian shore could be sucked down by Charybdis. Crataeis embodied the rocks themselves - the jagged cliffs, the hidden reefs, the sheer faces that rose from the sea without warning. The Roman writer Pliny the Elder, in his Natural History, records that in southern Italy there was a river called the Crataeis, known in legend as the mother of Scylla, a geographical marker that turned myth into landscape.

The parentage of Scylla was a matter of debate among the ancient poets, and Crataeis's role shifted depending on who told the story. Homer named her as Scylla's mother without mentioning a father. The mythographer Apollodorus, writing in the first or second century CE, said that Scylla was the daughter of Crataeis and Phorcys, an ancient sea god who was the son of Pontus, the primordial sea, and the brother of Nereus, the Old Man of the Sea. In some accounts Apollodorus gives an alternative mother, Trienos, whose name means "Three-Times," perhaps referring to the three rows of teeth in each of Scylla's six heads. The poet Apollonius of Rhodes, in his Argonautica, attempted to reconcile the conflicting traditions by saying that Crataeis was another name for Hecate, the goddess of witchcraft, ghosts, and crossroads, and that she and Phorcys were the parents of Scylla. This identification made sense to later writers, for Hecate too was linked to the dangerous margins of the world, the places where the known gave way to the unknown.

In another tradition, recorded by Semos of Delos, Crataeis was the daughter of Hecate and Triton, the fish-tailed herald of the sea, and she herself bore Scylla by Deimos, the personification of terror. This made Scylla a grandchild of Hecate rather than her daughter, a creature born of fear and the deep. The tragedian Aeschylus, in his lost play Prometheus Unbound, may have mentioned Crataeis in connection with the monsters of the sea, though the text does not survive. What is clear across all traditions is that Crataeis was a power to be reckoned with, a goddess whose very name invoked the crushing force of stone against wood and flesh.

Crataeis never appears as a character in her own right in the surviving literature. She is always the mother, the restrainer, the invoked power. But her absence from the narrative is itself significant. She is the force behind the monster, the ancient sea-goddess who gave birth to the creature that sailors feared above all others. When Odysseus called upon her, he was not praying to a distant Olympian but to the very spirit of the rocks that threatened to tear his ship apart. In that invocation lies the essence of Greek religion: the world was alive with powers, and even the most terrible places had their gods, and even the most terrible gods could be petitioned by those who knew their names.