The Furies had snakes for hair and blood dripped from their eyes. they also had bats' wings and dogs' heads. They were persecutors of men and women who committed parricide, killed a brother, or murdered a fellow clansman. Their effect on their victim was madness.
A famous legend about the Furies describes their relentless pursuit of the Theban prince Orestes for the murder of his mother, Queen Clytemnestra. Orestes had been told by Apollo to find the killer of his father, King Agamemnon, whom Clytemnestra had murdered. The Furies, heedless of his motives, tormented him until Orestes pleaded to Athena, who persuaded the avenging goddesses accept Orestes' plea that he had been cleansed of his guilt. When they were thus to show mercy, they transformed themselves, from being the Furies of frightful appearance into the Eumenides, meaning "kind-hearted."