Man
As Orpheus grew, it took Hermes some time to remember he wasn't as young as he once was. Part of it, he knew, was how young Orpheus seemed—the poor boy wore his heart on his sleeve, and his notebooks were filled with music, poetry, and dreams for the future.
But when Eurydice came, his eyes were alight with romance and tender love as they slept beneath the stars. And when she left, Hermes saw steel in his eyes, determination to get her back no matter the cost to himself.
Over the course of a single summer, Orpheus had grown from a poor boy to a young man, as Hades himself noted when the poet came crashing through his doors. But Hades was old, as immovable as his kingdom, and he'd been young once too.
A song of his and Eurydice's love wouldn't move him, Orpheus knew. But having loved and lost Eurydice, even if the circumstances were different, he could empathize with the king. He understood his love for Persephone, and his pain when she left.
And with his life and the lives of everyone he knew on the line, the young man sang the song Hades himself had forgotten.