Persephone never appears, but her shadow is what finally turns Odysseus around. He has been at the blood pit for hours, watching the shades come and go, talking to his mother and the dead heroes of Troy, when a cry rises somewhere in the distance louder than any sound he has ever heard. Everything stops. Even the dead go quiet. And then the thought arrives cold. The queen of the dead has not invited him. He is an intruder in her territory. Circe had warned him. Stay too long and the dead will not let you leave. He thinks of the Gorgons, creatures she might send, who turn men to stone. He would not die. He would stand there forever, conscious, frozen, surrounded by the dead. He runs. Persephone never has to lift a hand. The fear of her is enough.
Persephone
Queen of the dead. Unseen, but the reason a man knows when to stop walking deeper into the underworld.