If the Red wedding was anything to be shocked and pitied about, the episode “The Door” has absolutely torn apart the hearts of millions of Game of Thrones fans. Two of the most loyal, gentle and pure-hearted characters in the whole Song of Ice and Fire Universe – Everyone’s friendly giant Hodor and the Direwolf Summer met a tragic end guarding and protecting Bran Stark as the whole bunch were attacked by a large army of Wights and the White Walkers just because Bran couldn’t fall asleep and decided to go on a little trip while the rest of them were sleeping.
Unlike many of his previous visions where he used to freely spectate around without people noticing, he wandered around as he saw the Army of the dead (the wights like others could not feel his presence), and he saw the White Walkers leading the army of the dead. But suddenly out of nowhere he turned behind and saw the Night’s King who to his absolute surprise stared right back at him and touched his hand as if he could see him ( Is the Night’s King a greenseer too? ).
We saw that the Children of the Forest created the White Walkers to defend against the invading First men, but what if they accidentally selected a Greenseer as their test subject? Such a thought makes one afraid as to what consequences it might have for the Realm. The Night’s King left a mark on Bran Stark, a sort of a tracking chip which enabled him to trace him to the cave and break the magic spell set by the Children of the Forest to prevent him from entering the area. He took the party to the cave without an open invitation and massacred everything and everyone including Summer, Hodor, The Three-Eyed Raven and the Children of the Forest as they sacrificed themselves in order for Bran and Meera to escape and get a head start( We will surely see Benjen Stark/Coldhands in the next episode won’t we?!). Someone has to help them get to the Wall.
Bran is multitasking (sleeping/warging/greenseeing) all this while and witnesses the whole tragedy as he realises he was responsible for why young Wylis became Hodor, thereby realising he can alter the past. His only destination will be to reach the Wall and warn Jon and others about the catastrophe that is about to destroy Westeros and the realm. But as we know, the Wall is woven with the same magic like the one in the cave to prevent the White Walkers from crossing/entering it or finding about its location. What if Bran crosses the Wall and in doing so breaks the spells and allows the Army of the Dead to plunger through Westeros and destroy everything and everyone because he has been marked by the Night’s King?
The Wall will come down, Winterfell next and one by one the Southern kingdoms – all meeting their imminent doom as a certain Daenerys Targaryen is busy traveling to Westeros to claim the Iron Throne, oblivious to the threat of the White Walkers. What if Bran realises what a terrible mistake he has committed and goes back in time to prevent the Walkers from entering Westeros by Building The Wall, Winterfell and what not and invariably founding House Stark .
According to ASOIAF novels, a man named Brandon The Builder built the Great Wall with help from Children of the Forest’s magic to prevent the darkness from entering the continent and founded House Stark. Well, well it would be a real brain screwer if that guy turns out to be the same kid who screwed up Hodor and is being slaughtered by fans all over social media. But knowing George R R Martin and the producers, anything and everything is possible in how this epic fantasy comes to an end.