Castor and Pollux

They're Gemini today, but Castor & Pollux weren't always stars. Time was they were spurned as spawn of a swan. Twins they were, with different fathers. Not an uncommon thing back when.

Leda had Castor and his sister Clytemnestra by Tyndareus, a mere mortal. A Spartan king, but a mortal nonetheless. From the second egg (I did mention that Leda was a swan, didn't I?) hatched Pollux and his sister Helen. You know Helen. Launched a thousand ships and all. Their dad was Zeus, the Big God, master of disguise, who could easily change into a swan if he fancied one.

Castor and Pollux became Argonauts; accepted the award of Patron Saints of Voyagers; went on to rescue Helen. Castor, like many mortals, was into horseback riding. Pollux, like many immortals, preferred throwing punches in the ring. They hung out and had a lot of fun together.

Once they raped a couple of priestesses. That got them in trouble with a couple of other twins who claimed the priestesses for themselves. An imbroglio ensued, resulting in the death of three of the four. Naturally, Pollux, being immortal, was spared. But he couldn't stand to lose his brother, so he asked Papa Zeus to take him instead. Zeus compromised. He assigned them alternate days, first on Olympus as gods and then as dead mortals under the ground. So, you see, it worked out okay all around. Except on those alternate days.