It seems like the king of the gods, Zeus (Jupiter to the Romans), is always causing some kind of trouble. In this myth, he decides it's a good idea to let his brother, Hades, marry his daughter, Persephone. Zeus decides this, of course, without bothering to tell Persephone or her mother, Demeter, of his matchmaking scheme. It all blows up in Zeus's face, however, when Demeter causes famine to plague the earth. This myth is pretty interesting in that the all-powerful king of the gods gets punked down by a goddess. It looks like the patriarchal (male-dominated) system on Mount Olympus isn't quite as fool-proof as Zeus would like it to be.
We've got a lot more to say about Zeus. Check it out here.