Nemesis

Hesiod's Theogony places Nemesis among the small catalogue of children Night (Nyx) bears entirely on her own, without a father: Nemesis, "to afflict mortal men," appears in the same unbroken list as the Moirai (the Fates), Thanatos (Death), Apate (Deceit), and Eris (Strife), each a primordial force rather than a character with a developed story of their own. Where the Moirai govern the fixed span of a life and Thanatos ends it, Nemesis's domain is narrower and more moral: she exists to answer excess, restoring balance whenever a mortal, or a god, claims more good fortune, honor, or impunity than is properly theirs, the offense Greek myth calls hubris. Her clearest myth-in-action, rather than abstraction, is granting a rejected suitor's prayer to curse Narcissus with hopeless love for his own reflection, Ovid's version of exactly the kind of unearned favor her domain exists to answer.

Hesiod returns to her by name once more, in the Works and Days, in the passage describing the final stage of humanity's decline through the five ages. As the Race of Iron reaches its worst point, "Aidos and Nemesis, their sweet forms wrapped in white robes," abandon the wide-pathed earth for Olympus, leaving mortals with no defense against evil. Aidos personifies shame, the internal restraint that keeps a person from wrongdoing; Nemesis personifies the external check, the retribution that follows once shame has already failed. Their joint departure is Hesiod's image of a world with no working moral guardrails left, human or divine.

A separate, much later tradition gives Nemesis an actual narrative, one that has little to do with her role as an abstract moral force. In Apollodorus's Library, Zeus desires Nemesis, and she flees him by changing shape repeatedly, across land and sea, until she becomes a goose; Zeus, in the form of a swan, catches her in that shape, and their union produces an egg. A shepherd finds it and brings it to Leda, who keeps it in a chest until Helen hatches from it and Leda raises her as her own daughter. This version quietly displaces the far more familiar account, in which Zeus visits Leda herself as a swan and Helen is born to Leda directly. Apollodorus records both without reconciling them, which is itself typical of how far an already-old myth could diverge by the time a later mythographer tried to catalogue every version of it in one place.