Can I jump into this discussion brehs? I haven't been as involved in this thread as I have been in past years.
I like
@hexagram23 do not believe it's a fixed timeline. It's quite reasonable, and theoretically possible, to live in a multiverse with a fixed timeline or a multiverse with a paradox. The problem with this graphic, is that each scenario creates a life ending alternative, and each scenario is only described from the point of view of the time traveler.
Hear me out on this: I think the current rendition of Game of Thrones, i.e. from Bran's perspective in 2016, is the second rendition of a multiverse. (Think XMen days Future Past)
Bran giving Hodor a mental deficiency was an escape plan that he would have had to have learned to do to ensure success. If he had already learned/created the event, then that is proof of an original timeline. An original timeline should not be confused with the use of paradox, fixed timeline, or multiverse, it simply means T1.
That alone gives us reason to believe that in the original timeline, Wylis possibly failed to "hold the door", Bran desperately wargs into his body and creates a multiverse connection between the past and present. He also possibly dies because Hodor could not indeed "hold the door." However this death or survival doesn't matter to us, because we're no longer on the T1 timeline. In fact we could be on the T20 timeline and still wouldn't know. (Think Edge of Tomorrow) The possibility of it's existence is the most important aspect.
Some will say, "the ink is dry on the past." Well that's the beauty of a multiverse, the new loop, is just a copy of the past, up until the point of your time travel. And if you think the ink is dry on the past, you still have to explain: 1) how can Hodor be mentally crippled on a linear paradox timeline, without Bran warging from the present? 2) If Bran warged from the present, to change the past, and didn't create an additional timeline, then what happens to the original timeline in a single linear paradox, as the events would continue to repeat if the future is not changed.
The event of Wylis turning into Hodor is Hodor's paradox - as he is stuck to the timeline because of Bran - but it is not Bran's final ending, thus revealing the existence of a multiverse. Hodor isn't dead because Bran made him hold the door. Hodor is dead because Bran decided to venture into the past and walk among the Walkers.
We just saw Bran turn Wylis into Hodor, and we also saw Ned at the Tower. So now, from our perspective, there are 3 Game of Thrones timelines (that we know of) going on in parallel to each other, all at different intervals. And that still leaves that original timeline which the three eyed raven is trying to guide Bran to follow.