At the start, Persephone was Demeter's daughter, the Greek goddess of the earth.
You are such a sweet girl!
I love you mother
But eventually Hades, the lord of the underworld, kidnapped Persephone and forced her to be his bride and to live in the underworld with him.
You're coming with me!
Hades and Persephone loved it in the underworld but not Demeter. She did not like her daughter being near men far away from her mother. Demeter begged for Hades to let her go, but Hades wouldn't do it.
Eventually, a god named Zeus made an agreement that Persephone could come back to Hades every six months and return home for six months.
Whenever Persephone came back home to her mother, Demeter would be happy and give nature beauty and make the world nice and sunny.
But when Persephone was in the underworld, Demeter became depressed and refused to give nature beauty. This led to cold climates and lots of snow.