To aid in slaying Medusa, the gods offered Perseus a helm that granted him invisibility, as well as a shield with a mirrored surface. So the legend goes, he was able to use the former to obtain the element of surprise, and the latter to face her without meeting her petrifying gaze.
Of course, that’s only half the story.
What Perseus could not have known is that the mirror he carried served as the border between two worlds. On the other side, the Gorgons were fragile beings forced to live in subterranean caverns by human poachers. Their magic had been inverted: if ever their eyes met with those of a human, they themselves would turn to stone. They were forced to become masters of camouflage and trickery, for the kings and queens of the world above found them to be most valuable not as living things, but as statues.
In this realm, there also lived one named Me(deux)sa, cunning and swift, but bearing few reptilian qualities beyond the hands of a gecko. She was in hiding, skittering about the walls and ceiling of her underground kingdom quietly, for the cruel Perse(us) had come to make an ornament of her. She knew the angles of the cave intimately, but he was using his mirror to cast his gaze in unpredictable directions, a whirling pharos of death.
Cornered and afraid, Me(deux)sa knew that the only way out was through. She dropped down behind Perse(us)’s back, hoping to startle him and fill his jugular with the hemlock in her fangs. At that moment, his mirror caught her directly, throwing off her guard. When she peered through, however, her gaze caught that of another self. Serpent-headed Medusa stared into her, fearsome and terrible, grotesque at the moment Perseus’s sickle caught her neck. Something passed between them, ricocheting off her pupils.
As Perse(us) spun around, there was a new glimmer in Me(deux)sa’s eyes. The gods of an alien Olympus had condemned him to become his own tombstone.