Of three things Octavia was absolutely certain. One: she liked stallions. Two: her conductor expected grace and perfection from all her players. And three: the fact that she just drunkenly slept with Vinyl Scratch didn't match up with EITHER.
Hades, Lord of Death and God of the Underworld, is bored. Residing in Tartarus gets tiring for a God. So he decides to visit Equestria for a bit. And maybe make new allies so he can take over Olympus.