20Bringing Things Full Circle
All of Christopher Nolan's Batman films can stand on their own as independent superhero films, and in many people's opinion, this would make them better films. However, Christopher Nolan realizes that fans will connect these films together and Nolan enjoys putting the occasional easter egg referencing another film in the
future or past. Therefore when Nolan was creating The Dark Knight Rises he wanted the story to line up with his Batman story so far. He stated during the filming of Dark Knight Rises Nolan wanted to keep any references to Heath Ledger's Joker out of the film out of respect for him since his recent passing.
Therefore Nolan was stuck with trying to connect The Dark Knight Rises plot to the plot of Batman Begins. This is where the character of Talia Al Ghul and The League of Shadows come into play. Bane needed an origin story and Nolan didn't want it to take up too much of the film. Therefore Bane's origin unfolds as the plot does and we find out that Bane was part of the league of shadows. This explains his connection to Talia and his incredible knowledge of martial arts he uses against Batman several times during the film.