When Perseus entered the Gorgons’ home, Medusa was sleeping beside her sisters, Stheno and Euryale. Medusa alone was mortal. Her sisters could not be killed. After Perseus severed Medusa’s head, Stheno and Euryale awoke to discover what had happened. They did not sacrifice themselves, as some modern retellings claim. They spread their wings and pursued him, determined to avenge their sister. Perseus escaped only because he wore the helmet of Hades, which concealed him from their sight. Ancient poetry remembers Euryale’s grief through her piercing cry. Pindar wrote that Athena later created flute music inspired by the terrible lament that rose from Euryale as she chased her sister’s killer. Stheno and Euryale were immortal, yet their immortality offered no protection from grief. They could pursue Perseus, but they could not bring Medusa home. The myth does not tell us that they died for their sister. It leaves them alive, grieving and searching for a man they could no longer see.