Castor and Pollux are twins, but Castor is mortal, and Pollux is a demi-god because their mother, Leda, slept with her mortal husband and with Zeus on the same night (bad Leda, or actually, since Zeus seduced her by pretending to be a swan, bad Zeus!)

One day, Castor and Pollux decide to abduct Phoebe and Hillareia and marry them (in ancient times "rape" meant "abduct", although abduction was doubtlessly followed by sexy time at some point).

However, Castor and Pollux were not the only mythical heroes to have the hots for Phoebe and Hillareia and they are soon challenged by Idas and Lynceus, who kill Castor. Pollux then persuades Zeus to let him share his immortality with Castor, and both of them become the constellation Gemini.