my 2cents... Its not time travel. Ned heard him and NK and Hodor saw him when they shouldnt have , but he's not physically there for everyone to see and interact with. Its not like the time travel in say, Terminator. Its more a form of vision magic, which is hardly a new idea in fantasy. Not sure why people are having a problem with this in a story that has reanimated corpses, Frankenstein, fairies throwing holy hand grenades,and from the beginning has been building a subplot of the coming medieval zombie apocalypse. The story opened with WWs, so Ive always kind of expected it to end with them. Hardhome pretty much told you where the story was heading. IMHO the Tyrells and Lannisters have doomed themselves, and Im expecting Daeny to waltz into the throne room and plant her pretty butt on the throne with all her enemies dead. The final showdown will be with the White Walkers not the remaining lords of Westeros, who continue to destroy themselves.