All of us remember the Tower Of Joy scene. Bran is taken there by the Three eyed Raven and Bran calls out to Ned and Ned turns around to see him.
Did he hear Bran?
If yes, then maybe back in time, Bran’s voice is heard but he’s not visible. So this might be possible that Bran tries to pacify The Mad King to stop the War against Baratheons and Starks when The Mad King gets psyched because all he hears is voices in the air. What if this drives him mad and he starts getting psyched and asks Jaime to burn ’em all!
This means that Bran might be behind the beginning of all of this mess! Also, a theory suggests that Bran might also be the Three Eyed Raven from the future who’s trying to fix the past this way!
Game Of Thrones 