Game Of Thrones Season 6: 6 Crazy Fan Theories About Bran Stark
5. He Is The Three-Eyed Raven
"The time has come. For you to become me."
They're the words of the Three-Eyed Raven in The Door, despite the fact that Bran isn't ready. He's ruined the cave magic, meaning the Raven's time is up, and Bran has to take on the mantle.
But what if he's speaking incredibly literally?
This theory posits that Bran warged into Brynden Rivers of the past (the Three-Eyed Crow from the books, though the show is less explicit in revealing his true identity), and then controlling him makes him go to the weirwood tree, become the Three-Eyed Raven, and then start communicating with Bran. This leads Bran on a path to the tree, where he learns from the Raven, and then leaves the tree as we've seen in the show.
This means that Bran was always the Raven, and went back in time in order to train himself, and thus give him the power needed to potentially save Westeros.