Persephone, also known as Kore or Proserpina, was the Greek goddess of the Underworld, springtime, flowers and vegetation. She was the daughter of Zeus and Demeter, and later wife to Hades.
Persephone was eventually abducted by Hades, the king of the Underworld, who wanted a bride. Demeter was upset of this, and as goddess of agriculture and fertility, refused to fulfil her duties, which led to massive droughts and famines in the realm of the humans. Zeus, worried about humanity, contacted Hades and begged him to release Persephone. Hades agrees, but it is also revealed that Persephone had eaten a pomegranate, which confined her to the Underworld for half of the year.
The time of the year when Demeter and Persephone would be together became spring and summer, while the time when she returned to the Underworld would be autumn and winter.