Polydeuces was known as a boxer and won many Olympic events. He was also one of Jason's Argonauts on Jason's quest for the golden fleece. During the quest, Polydueces proved himself by killing an evil king and allowing the quest to continue.
When the twins returned from the quest, they got in a dispute with two other men which was followed by a terrible battle. During this battle, Castor, the mortal, was killed. Polydeuces was terribly saddened by this and cried to his father Zeus. Zeus listened to Polydueces and decided to let Polydeuces and Castor spend alternate days on Olympus, home of the gods, and in the underworld. Zeus also raised the twins image to the sky forming the constellation Gemini or the twin stars.