The Greek Myth of Gemini is like this: Zeus, disguised as a swan, impregnated Leda who had the twins Castor and Pollux, born from an egg. Pollux, unlike his brother Castor, was immortal. The two were very close and careful with each other. In a nearby region, they met and fell in love with the sisters Febe and Ilaira. But they were brides and they decided to kidnap them. The newlyweds, Idas and Lynceus, pursued the brothers. In the ensuing confrontation, Idas threw his spear mortally wounding Castor. Pollux, maddened with rage, killed everyone around him. Pollux, desperate, asked Zeus to transfer his immortality to Castor.
Not knowing what to do, Zeus grants the request, and as soon as Castor receives the light of immortality, Pollux begins to die. Castor then asks Zeus not to let his brother die and to exchange his life for his. Zeus grants the request and while one was on earth, another would be in heaven. Dissatisfied with not always being together, Castor and Pollux were transformed into the constellation of Gemini, where they would be together forever.
Didn't you find the Greek Myth of the Sign of Gemini interesting?