In Greek mythology, Persephone spends part of every year in the underworld because she ate pomegranate seeds there

Explanation

Eating the food of the dead bound her to Hades. Her time below is said to explain the seasons: Demeter mourns, and nothing grows. Fun fact: the sources disagree on the details. The Homeric Hymn gives her a third of the year below, while the most popular retelling has six months.