Persephone registers 64 times at rank 1614 on female pets. Greek mythology has always been a naming vein for pets, and Persephone is its most dramatically loaded option: the goddess who spends half the year in the underworld, whose departure causes winter and whose return brings spring. It's a name that owners choose when they want maximum mythological weight in a single word.
The Mythology Angle
Persephone is the daughter of Demeter and Zeus, queen of the underworld, and the symbolic anchor of the seasons in Greek myth. As a pet name, it attracts owners drawn to dark academia aesthetics, the same crowd who names cats Hecate or Hades. A black cat named Persephone is almost a cliche at this point, and it's a perfectly good cliche. The human name comparison is at /names/persephone.
Sound and the Nickname Problem
Per-SEF-oh-nee is four syllables, long enough that daily use will almost certainly produce a nickname. Percy, Percie, Seph, and Sephy are all in circulation. Owners who choose the full name find it lands well with cats. For dogs, Percy tends to be the working name.
The Counter-Reading
Persephone signals very specific owner aesthetics: literary, mythology-aware, unbothered by complexity. For Maine Coons and other large, imperious cats, it fits. For a golden retriever, it may be more name than the dog needs.