Actor Isaac Hempstead Wright spoke to The Australian and says Bran has never been more alone or more crucial to the plot.
Q: Is he even Bran anymore?
A: Not really. On top of all that he has now got this huge responsibility upon his shoulders of being the Three-eyed Raven he remembers everything that's ever happened in the universe ever. He's got all this knowledge about Jon Snow and all the knowledge about the origin of the White Walkers, which may come in handy for defeating them. It all means that Bran is a really, really valuable asset for Westeros right now. He must make sure this information gets to the right people in time. As such, at the start of season seven Bran is on a mission to get to the right place and save the day.
Q: What's it been like playing a character who began as a boy but is now barely human?
A: It was tricky to work out how exactly we would play him. It was clear that he needed to have this kind of emotionless, soulless, slightly mysterious aura to him, but we didn't want it to be really dull and monotone. Basically, David and Dan said read the Watchmen comics: it's like Dr Manhattan. Bran's got this whirlwind of information spinning around the whole time: "Oh, that happened, that happened, that happened." It's like he's not really in any fixed time.
Q: Crucially he is one of the few who knows what the enemy in the Great War is
A: Yes, in fact Bran more than anyone, because he is now basically the arch enemy of the Night's King. They are sworn enemies from the first day of time, the Three-eyed Raven and the Night's King. So Bran knows better than anyone, I think, the terror and fear they should all be feeling with this threat looming over them.