Persephone, Greek goddess of the Spring season, is the daughter of the king of gods Zeus and the goddess of the harvest Demeter., and a key figure in Greek mythology. To call Persephone goddess of the Underworld is technically correct, but only to a degree. She does indeed live in the Underworld during the Fall and Winter seasons, but during the Spring and the Summer she returns to the Earth to inspire the renewal of life. Upon her return each year new plants grow, trees get back their leaves and create fruit, and animals come out of hibernation and find a mate. Without her and her mother, the goddess of the Harvest, life on Earth would quickly expire.
At one point, sewing the seeds of life was the only role for Persephone. "Goddess of the Underworld" was not a title she ever thought she would carry, and generally not a title most of the goddesses wanted. The Underworld, ruled exclusively by Hades, was where human souls went after they died. Hades and his brothers, Zeus and Poseidon, drew lots for control over different parts of the universe. Zeus won the sky and heavens, Poseidon the earth and sea, and Hades drew the fiery pits of the Underworld. Most of the gods preferred the Heavens, and none enjoyed visiting the Underworld much. After many years ruling alone, Hades had finally had enough and told Zeus that he needed a companion.
Knowing that no goddess was keen to live in the land of the dead, Zeus offered his own daughter, the Spring maiden Persephone, to be the goddess of the Underworld. At the time this seemed to Zeus like a perfect idea - he would marry off his single daughter and at the same time he wouldn't anger any of the other gods by sending one of their daughters to the Underworld. There was only one problem. Persephone was not his daughter alone.
When her mother, Demeter,
found out what Zeus had done she was furious. Demeter threatened to
destroy every crop and every harvest if her daughter was not returned.
This put Zeus in a bind. On one hand he couldn't back out of his
promise to Hades, but on the other hand with Persephone in the
Underworld and Demeter refusing to do her duty, there was no one left to
grow the crops, without which all living things on Earth would die.
Though he was often depicted as a proud warrior, Zeus also had a reputation for being a fair mediator of disagreements between the gods, and this, was perhaps, his finest hour in that regard. In order to half-please all parties, Zeus decreed that Persephone would spend half of the year in the Underworld, when she was not needed on land, and the other half of the year with her mother sewing the seeds of life. This is the ancient Greek explanation of the four changing seasons.