Stheno

Stheno is the oldest of the three Gorgon Sisters. She is characterized as a beautiful woman with wings, red snake-like hair and bronze claws. Though Stheno is the smallest and most lithe of the three Gorgon sisters, she is easily the most powerful.

Succubus Queens
Following Medusa's death Stheno and Euryale sought out the Queens of Hell in order to avenge their sister's murder at the hands of the Olympians. In exchange for helping the Succubi attack the Olympians, Stheno agreed to have her memory of Medusa erased. The Succubus Queens saw this as an opportunity to gain powerful servants and betrayed Stheno and Euryale by erasing all their memories of their lives together. Unlike Euryale who required a curse of apathy in order to stay true to the cause of the succubi, Stheno was already hardened by the death of her younger sister and became cold, unforgiving and merciless. She killed whoever became a problem for the Succubus Queens and was adopted by Igret as her personal assassin.