Medea figured into the story of Jason and the Argonauts after Jason arrived in Colchis to claim the fleece as his own. King Aeetes of Colchis promised to give it to him only if he could perform certain tasks. First, Jason had to plow a field with fire-breathing oxen that he had to yoke himself. Then, Jason sowed the teeth of a dragon into a field. The teeth sprouted into an army of warriors. Jason was quick-thinking, however, and before they attacked him, he threw a rock into the crowd. Unable to decipher where the rock had come from, the soldiers attacked each other and defeated each other. Finally, Aeetes made Jason fight and kill the sleepless dragon that guarded the fleece. Jason then took the fleece and sailed away with Medea, who had fallen in love with him and helped him win the fleece. Medea distracted her father as they fled by killing her brother, Apsyrtus. In the flight, Atalanta was seriously wounded but healed by Medea.
The Argo then came to the island of Crete, guarded by the bronze man, Talos. Talos had one vein which went from his neck to his ankle, bound shut by only one bronze nail. Medea cast a spell on Talos to calm him; she removed the bronze nail and Talos bled to death. The Argo landed.
While Jason searched for the Golden Fleece, Hera, who was still angry at Pelias, conspired to make him fall in love with Medea, whom she hoped would kill Pelias. When Jason and Medea returned, Pelias still refused to give up his throne. Medea conspired to have Pelias' own daughters kill him. She told them she could turn an old ram into a young ram by cutting up the old ram and boiling it (alternatively, she did this with Aeson, Jason's father). During the demonstration, a live, young ram jumped out of the pot. Excited, the girls cut their father into pieces and threw them into a pot. Pelias did not survive.
Having killed Pelias, Jason and Medea fled to Corinth.
When Jason deserted Medea for Glauce, daughter of the Corinthian King Creon, she killed Glauce, Creon, and her own two children and fled to Athens. Alternatively, Jason married Creusa, daughter of Creon. Medea got even by giving Creusa a cursed dress that stuck to her body and burned her to death as soon as she put it on.
Some said Medea married Achilles.
Fleeing from Jason, Medea made her way to Athens and married Aegeas, (one son: Medus) father of Theseus, whom he had abandoned as a baby. When Theseus returned to Athens, he did not reveal his true identity. He was welcomed by Aegeas, who was suspicious about the stranger who came to Athens. Aegeas' wife, Medea, tried to have Aegeas kill Theseus by asking him to capture the Marathonian Bull, but Theseus succeeded. She tried to poison him but at the last second, Aegeas recognized the sandals, shield and sword and knocked the wine glass out of Theseus' hand. Father and son were reunited.
Medea, with Medas, fled Athens. She founded Media.