Medea

Before Jason, she was the most powerful person in Colchis.
Granddaughter of Helios the sun, student of Hecate herself, a woman who understood the deep structure of the natural world at a level of fluency that no one before or since has matched. She was not a witch. She was a scientist of the ancient kind - precise, systematic, brilliant - and her knowledge was simply hers, before the world got hold of it and decided what it should be used for.
Then the Argo came into the harbor. Then Jason looked at her and saw the solution to his problem. Then she looked at Jason and saw, for the first time, the company that exceptional aloneness had been waiting for without knowing it was waiting.
She saw clearly. She chose anyway.
She gave him the bulls, the dragon, her brother in pieces in the sea. She gave him seventeen years of marriage and children and the life he built in Corinth, which was built entirely on her knowledge and her power and her willingness to spend herself in his service. And then he told her - the way men tell women things they have already decided - that he was going to marry someone else.
He was not just leaving her. He was un-making her.
She would not be un-made.
Medea is told in two voices: Medea's own, moving from the sanctuary in Colchis through the Argo and Corinth and the fire to Athens, where she still is; and her nurse's, the woman who was given to her at birth and never left, who was twelve years old when they walked together to Hecate's sanctuary and has been walking beside her ever since. The nurse who saw everything, understood everything, and could not stop any of it.
Not the monster. Not the jealous witch. The woman who was made by extraordinary gifts and extraordinary loss into something the world did not have a category for - and the woman who loved her through all of it, including the parts that could not be forgiven.