Game of Thrones has a ton of different storylines going on, but one that didn't seem to make much sense was Bran Stark and Jojen Reed. One fan theory suggests Jojen was hiding the full truth from Bran, and that he actually foretold the ending of the entire show.
The theory is pretty extensive, so bear with us. During Season 3, Jojen appeared to Bran in a dream. Bran already had some warg-like powers, such as seeing his father in the crypt when he was beheaded, and his weird dreams. But Jojen later found Bran and helped him develop his greensight, and find his way to the Three-Eyed Raven.
But Jojen also had more of a prophetic power that Bran doesn't seem to have. After Jojen dies, his sister Meera goes to talk to the Three-Eyed Raven, who tells her Jojen knew he would die, but came anyway. And when Jojen, Bran, Hodor, and Meera were captured at Craster's Keep, Karl comes to rape Meera, but Jojen tells him he has seen him burn, and saw snow bury his bones. Eventually, Karl's body is burned with the others killed during the raid led by Jon Snow.
If Jojen saw his own death and Karl's (and even Ned Stark's), he certainly could have seen Bran's, but just didn't tell him. While captured at Craster's Keep, Jojen does have an ominous discussion about Bran's end, which seems to hint he knows when it's coming. "This isn't the end," Jojen tells Bran. "Not for you. Not yet."
Meera then asks him, "How will we know the end?" Jojen then looks at his hand and sees it on fire. He responds, "You'll know."
When Jojen says it wasn't the end, "not yet," it seems to imply he knows when it will come. And the fact that he sees his hand on fire, perhaps means Bran's death will include fire. Seems fair enough. But this theory decides to take it a few steps further...
When Jojen saw his hand on fire, it was incredibly reminiscent of Jon Snow killing the wight in Season 1. When the corpse comes back to life and tries to attack the Lord Commander, Jon throws fire at the creature, using his right, the same hand that Jojen saw on fire.
This connection between Bran and Jon also makes sense, since they were close in the beginning of the show (and are cousins), and all of Bran's most important revelations were about Jon (his birth and the marriage of his parents). The theory suggests that this means Jon will play a part in Bran's death, and possibly be the perpetrator. In the Azor Ahai prophecy, The Prince That Was Promised must kill a loved one, and if Jon Snow is that prince, perhaps he will have to kill Bran.
Guess we'll have to wait until Season 8 comes out in 2019 to know for sure. You can watch the full theory here: