Isaac had died to destroy the First Marker that had been buried underneath Equestria, killed by an avatar of the Marker's consciousness, and had embraced the end with a tired smile. That is, he rested until he was resurrected by those who were drifting in the aftermath of the Marker's fragmented power. Forced into a Pony body, he will learn to adapt to the new Equestria that survived what should have been the apocalypse.