King Aeetes' most valuable possession was a golden ram's fleece. When Jason and the crew of the Argo arrived at Colchis seeking the Golden Fleece, Aeetes was unwilling to relinquish it and set Jason a series of seemingly impossible tasks as the price of obtaining it. Medea fell in love with Jason and agreed to use her magic to help him, in return for Jason's promise to marry her.
Jason fled in the Argo after obtaining the golden fleece, taking Medea and her younger brother, Absyrtis, with him. King Aeetes pursued them. In order to delay the pursuit, Medea killed her brother and cut his body into pieces, scattering the parts behind the ship. The pursuers had to stop and collect Absyrtis' dismembered body in order to give it proper burial, and so Jason, Medea and the Argonauts escaped.
After the Argo returned safely to Iolcus, Jason's home, Medea continued using her sorcery. She restored the youth of Jason's aged father, Aeson, by cutting his throat and filling his body with a magical potion. She then offered to do the same for Pelias the king of Iolcus who had usurped Aeson's throne. She tricked Pelias' daughters into killing him, but left the corpse without any youth-restoring potion.
After the murder of Pelias, Jason and Medea had to flee Iolcus; they settled next in Corinth. There Medea bore Jason two children before Jason forsook her in order to marry the daughter of Creon, the king of Corinth. Medea got revenge for Jason's desertion by killing the new bride with a poisoned robe and crown which burned the flesh from her body; King Creon died as well when he tried to embrace his dying daughter. Medea fled Corinth in a chariot, drawn by winged dragons, which belonged to her grandfather Helios. She took with her the bodies of her two children, whom she had murdered in order to give Jason further pain.
Medea then took refuge with Aegeus, the old king of Athens, having promised him that she would use her magic to enable him to have more children. She married Aegeus and bore him a son, Medus. But Aegeus had another son, Theseus. When Theseus returned to Athens, Medea tried to trick her husband into poisoning him. She was unsuccessful, and had to flee Athens, taking Medus with her. After leaving Athens, Medus became king of the country which was later called Media.