Bane has the most screentime as a villain in the film and gets all the cool action moments. He's definitely the decoy Ra's al Ghul of the film (Ken Watanabe in Batman Begins), who was shown giving orders and I think Bruce Wayne was supposed to replace him and attack Gotham . Except Bane doesn't die 40 minutes into the film, but he kind of goes out in a similar fashion (or like Rachel tasering Scarecrow) and then is forgotten about as the next set piece is set up. Bane at least became wiser than Talia that Batman had to die in order for the plan to succeed after his teary tender moment with her and she says bye-bye to him.
Talia is Ra's al Ghul's heir, who set her sights on destroying Gotham when her father died as a result of Batman's actions and she lost any resentment toward her father. She wasn't excommunicated from the League, but with her father gone it's clearly her that brought Bane back into the organization that cast him out. It's her family drama that makes up just about all of the flashback time in an attempted mislead to make the audience think it's Bane like Bruce did. It's her that hides in the shadows and hides behind a frontman just like daddy. She's rich like her father became.* She's accustomed to barking orders, even to Bane, who is her friend and protector. It's her fusion bomb and her detonator. It's her that dies last, gloating.
*Neeson said Ra's al Ghul was very rich, even if it didn't come across in Batman Begins, "I think he's as rich as Bruce Wayne, and has access to enormous, enormous funds of money. And he's like Bruce Wayne. He wants to defeat evil and corruption in the world." "And has developed a way of doing that...without revealing too much." Variety reported a spoiler in early 2004, "Liam Neeson plays the villain, Ra's Al Ghul, a wealthy international terrorist."