An Abyss Watcher is flung into Equestria after the Ashen One's secret betrayal. Finding someone to hold onto, he discovers new purpose under the guidance of the moon.
Seath the Scaleless was meant to be slain by the Chosen Undead, instead he finds himself wrenched from Lordran just before dying and abruptly tossed into a new role as the teacher of a kindred spirit: a pony called Twilight Sparkle.