Persephone

 was the wife of Hades, ruler of the Underworld. (PROSE: Katarina in the Underworld) She was a daughter of Zeus and a sibling to Apollo, Athena, Hermes, Artemis, Castor and Pollux, Dionysius, Hebe and Minos. (PROSE: Deadly Reunion)

Persephone saw good in Katarina and brought the First Doctor to the Underworld so he could help Katarina in her journey. When Hades' judges ruled that Katarina was neither good nor evil, Persephone convinced Hades that Katarina was good, and Hades allowed her to enter the Elysian Fields. (PROSE: Katarina in the Underworld)