The main problem with the “Night King” theory is that Bran cannot warg people in the past, he can only warg them in the present. What happened in the Hodor episode (The Door) was that Bran (who was greenseeing the past while physically in the present) warged Hodor in the present which connected him to Willis (young Hodor) in the past. The connection was between Bran and Hodor not Bran and Willis (Bran → Hodor → Willis → Hodor). Bran can connect to and change the past through warging someone in the present who also exists in the past that he is greenseeing (through their eyes aka a green dream). He can change someone’s past (and present) by connecting their past to their present.