The Gemini Myth

Castor and Pollux were twins who, though they shared the same mother and were born at the same time, had different fathers. Their mother was Leda, Castor’s father was a Spartan king called Tyndareus while Pollux could claim Zeus as his father.
The twins were great fighting men and fine athletes. Together they were known as The Dioscuri or ‘sons of Zeus’.
As the twins grew they were involved in many heroic adventures, one of which was joining Jason in his search for the Golden Fleece. Castor and Pollux had a sister called Helen who was greatly admired by Theseus of Athens, the same Theseus who in later years became famous as the slayer of the Minotaur in the Labyrinth below Crete. Disliking Theseus the twins forbade him from seeing their sister. Ignoring this Theseus kidnapped Helen and held her prisoner in Athens. Castor and Pollux waited until Theseus was away from the city and promptly stormed Athens and took Helen back to Sparta.
The twins had two cousins, also twins, called Idas and Lynceus. All four were great friends until Castor and Pollux ran off with two sisters who were due to marry their cousins the following day. For a long time the cousins were bitter enemies. Eventually the four forgot their differences and became friends again.
One day Castor told them of a plan he had devised to raid the cattle herds that grazed the plains of Arcadia in northern Sparta. The raid proved far easier than they had anticipated and was a great success. However they soon began to argue over how best to divide the spoils. Castor insisted he and his brother should have the greater number as it had been their plan. Idas pointed out that as they had shared the danger equally the cattle should be divided in the same way. As the argument became more heated Idas reached for his spear and hurled it at Castor piercing his heart. With a cry Castor fell dead at his brother’s feet. Furious at this cold blooded murder, Pollux drew his sword and struck at Lynceus who soon lay dead beside Castor. As Idas ran forward to avenge his brother a thunderbolt spitting fire and sparks struck him, killing him instantly. Gazing up at the heavens, Pollux saw Zeus staring down. Zeus had been watching the fight and had saved Pollux as he was a favourite son of his.
Pollux lay his brother’s body over his saddle and with a heavy heart journeyed home where he buried Castor with all the honour a king’s son deserved.
The brothers had never been separated before and Pollux pleaded with Zeus to reunite them. But being a son of Zeus and therefore immortal, he could not live in the underworld. Zeus, taking pity on his son decreed that the twins should spend alternate days together on Olympus and in Hades. Thus they would be reunited and share each others world together for all eternity.