Persephone is the wife of the Lord of the Dead (unofficial) and the daughter of the goddess of spring (Ceres (unofficial) most likely).
Behind the scenes[]
Persephone originates out of Greek myth.
In the official lore, KQ6 and related material, the land of the Green Isles is said to be tropical and have the single season of spring controlled by the druids.Though to be fair some of the islands appear show characteristics of temperate zones (Isle of the Beast) or colder regions (Isle of the Mists).
TSL suggests that the land has all four seasons, and that Spring and Summer take up half the year.
In KQ lore, if Persephone existed she would likely be the wife of Pluto the ruler of Hades rather than Samhain (there are multiple lords of Death in KQ lore).
In KQ6 its stated that Samhain has never known love, and cannot know love following his curse from the gods. It states that he was left mateless and had no companionship. Therefore he had no wife in official lore.