Aeson. In Greek mythology, Aeson was a king of Iolcus in Thessaly.
Aeson was the son of Cretheus and Tyro. He had two brothers Pheres and Amythaon.
Through his mother Tyro who consorted with the sea god Poseidon, he had two half-brothers, Neleus and Pelias. Aeson was the father of Jason and Promachus with Alcimede, daughter of Phylacus and Clymene.
Other sources say the mother of his children was Polymede or Polymele, or Polypheme a daughter of Autolycus, Amphinome, Theognete, daughter of Laodicus, Rhoeo or Arne or Scarphe. Pelias was power-hungry and he wished to gain dominion over all of Thessaly.
To this end, he banished Neleus and Pheres and locked Aeson in the dungeons in Iolcus. Aeson sent Jason to Chiron to be educated while Pelias, afraid that he would be overthrown, was warned by an oracle to beware of a man wearing one sandal. Many years later, Pelias was holding the Olympics in honor of Poseidon when Jason, rushing to Iolcus, lost one of his sandals in a river while helping Hera, in the form of an old woman, cross. When Jason entered Iolcus, he was announced as a man wearing one sandal. Suspicious, Pelias asked him what he would do if confronted with the man who would be his downfall. Jason responded that he would send that man after the Golden Fleece. Pelias took that advice and sent Jason to retrieve the Golden Fleece. During Jason's absence, Pelias intended to kill Aeson