AKA: The Conquerer?
Despite his conception being a huge massive plot point, the show has struggled to figure out what on earth it was doing with William. William's existence is a huge shift in the show's normal, and the show wasn't always on board with those changes, and they clearly had no idea where they were going with the idea that he has psychic powers. But with the finale barreling down on them like a proverbial train, the time had come to come to a decision point with his story, to as the saying goes, shit or get off the pot.