If the show is up to its old tricks, this could explain why we haven't seen the Night King or Viserion in any of the shots. Contrary to the plan, what if the Night King isn't going with the rest of the White Walkers to Winterfell, but taking Viserion to...King's Landing? Not only does this throw a wrench in the Starks' plan to use Bran to lure the Night King out into the open, but it would, as another user pointed out , be an easy way for the Night King to destroy the one thing the humans are fighting for: the throne.