Medea

Medea may have killed her brother after she betrayed her father. It therefore should not be too surprising that Medea, as the woman scorned, did not exhibit what we think of as motherly instincts. When the Argonauts arrived at Medea's homeland of Colchis, Medea helped Jason steal her father's golden fleece. She then fled with Jason and may have killed her brother in her escape. She lived together with Jason like a married couple long enough to have two children, but when Jason wanted to officially marry a more suitable woman, Medea committed the unthinkable and murdered their children.