She's been a big meanie to the mortals recently, but there should still be some horses who worship her! They could dabble in dark magic and make sacrifices and have weird handshakes :D
I really love the Fall of Lucifer idea too and since all the gods seem to like making babies with mortals, could you imagine the unlucky mare/stallion getting swallowed up by some monster underground???
That'd be an interesting plot to involve all the gods and the mortals in where they're all like 'what was that????'
See the Hades/Persephone myth by what I mean