The story of Gemini:

This sign stems from the Tale of Castor and Pollux. Castor and Pollux were half-brothers. Leda was pregnant to her husband when she was seduced by Zeus, Castor was born of Tyndareus and Leda, Pollux was born of the affair between Zeus and Leda. The twins grew inseparable as time went on. One day, Castor was killed in a battle. Pollux was so grief stricken that he took his own life to join his brother at death. In honor of the brothers' great love, Zeus placed them among the stars.