astor and Pollux were always represented as living just before the Trojan War, at the same time as Theseus, Jason and Atlanta. They took part in the Calydonian boar-hunt; they went on the Quest for the Golden fleece; and they rescued Helen when Theseus carried her off. But in all the stories they play an unimportant part except in the account of Castor's death, when Pollux proved his brotherly devotion. The two went to the land of some cattle owners, Idas and Lynceus. There, Idas made angry in some way about his oxen, stabbed and killed Castor. It has been accounted that the dispute was caused by the two daughters of the king of the country, Leucippas. Pollux stabbed Lynceus, and Zeus struck Idas with his thunderbolt. But Castor was dead and Pollux was inconsolable. He prayed to die also, and Zeus in pity allowed him to share his life with his brother, to live, half of their time beneath the earth, and half in the golden homes of heaven, meaning one day in Hades and the next in Olympus.

It was this strange request that eventually lead to Apollo asking Hermes:

"I say, why do we never see Castor and Pollux at the same time?"
"Well," Hermes replies, "they are so fond of each other that fate decreed one of them must die and only one be immortal, they decided to share the immortality between them."
"Not very wise, Hermes. what proper employment can they engage in, that way? I foretell the future; Aesculapius cures diseases; you are a good messenger - but these two - are they to idle away their whole time?"
"no, surely they are in Poseidon's service. Their business is to save ships in distress"
"Ah, now you say something. I'm delighted that they are in such a good business"

Two stars were supposed to be theirs: The Gemini, the Twins. They were always represented as riding splendid snow white horses, Castor being more distinguished above Pollux in his horsemanship, Castor was known as the tamer of horses.