Sam and Dean are hunting a big bad that requires something very special for a summoning ritual. A scale of Medusa. The boys have run into a few Gods and monsters from ancient Greece, but no one has seen or heard anything of Medusa in thousands of years. So they call up their friend Bobby to help them with some research. Bobby is able to track down Medusa as well as an amulet that will help keep him turning into a statue if she uses her powers on him. Hiding amongst humans has given Medusa thousands of years of practice avoiding capture, and she gets the jump on Bobby. Medusa is enraged that her powers didn't work on him, so she ties him up to get answers. As it turns out, Medusa actually needs something from Bobby too. It's been millennia since she has laid eyes on a human male that wasn't instantly turned to stone. She needs the seed of a man to make new offspring. So Medusa and Bobby make a deal, one of her scales for a load of Bobby's cum. Since Bobby is tied up, Medusa needs to extract Bobby's seed herself. She allows Bobby to leave with her scale, and his life, but not his dignity.