Stheno and Euryale

Stheno and Euryale are both witches and monstrous Gorgons. They are the older sisters to Medusa. They made their first appearance in the e-book novel Let Gorgons Be Gorgons.

History
Medusa was the most powerful of the sisters by far, but she had a mortal lifespan. Stheno and Euryale were immortal, but weaker on their own.

In the days of ancient Greece, when the Greek gods ruled the world, The Elders sent the sisters to Greece to check out what was happening. While they were checking on the Gods, their younger sister Medusa was raped by Poseidon, and was then cursed Athena. Enraged, Stheno and Euryale went after Athena, had cursed Medusa’s sisters as well after they came after her in a quest to avenge/save their younger sister. Years later, their younger sister Medusa was later murdered by Perseus at Athena's bequest.

Years later, in 2009, they resurrected Medusa using the magic of The Charmed Ones. Once restored, they caught their younger sister up on everything that had happened since her death; they flooded her mind with images from their own mind, things that they had seen. They then tried to get Medusa to join their plan of revenge. Medusa refused at first, she had no need for revenge; Athena, Perseus and Poseidon were all dead and could no longer harm her. However, Medusa felt indebted to her sisters and believing that they were her responsibility, agreed to help them. However, Medusa came to quickly realize that her sisters were out of control.

The sisters action drew the attention of the charmed sisters, which ended in a big battle between the sisters at the Nexus of the All. The sisters were all evenly match; Medusa and her sisters were able to match Prue and her sisters, power for power. However, Phoebe was able to bring the battle to and end by pulling images from the past from her own mind and sharing them with Medusa. She showed Medusa some of her Paige's most heroic deeds and the work of the Charmed Ones as well. Phoebe filled her mind with images of some of their greatest battles, and all the Innocents they’d protected— both during their time with Paige, and the early days with Prue. Then she pulled up her most recent images with all four sisters working together. She was able to convince Medusa that Paige was not to blame for Athena's actions.

Phoebe then informed Medusa that Stheno and Euryale had secretly been working with a former cupid who had used his own powers to force a woman to love him. And in the process had destroyed that woman's life. Enraged, Medusa turned Stheno and Euryale into stone.