One of the greatest surprises of TDKR was that Bruce was given at last a great romantic interest. And I'm not talking about Talia. Selina Kyle wins this hands down.
In Begins and TDK, Rachel Dawes filled a role of the romantic interest, but it was different. She represented hope for a better life, and Bruce idealized her to the point he didn't realized that, at the end, she didn't fully share his viewpoints and goals. That is not necessarily bad, because she had her own arc. She really loved Bruce, but as she said at the end of Begins, the man she loved didn't fully returned. So she was split inside. Then came Harvey Dent into her life and she saw something better for her, thinking that Bruce could never stop being Batman. In TDK that's her deal, and she makes a choice, a choice Bruce didn't know because Alfred didn't want to hurt him even more.
And then, in TDKR, eight years later we encounter and older Bruce who is frozen in time. Batman is no longer needed, and Bruce has nothing else to live for. Though it isn't an instant process. We learn that he tried to help people, with the donations of the Wayne Foundation to orphanages, and the energy project. And when that project seems to dangerous it is another defeat.
Then we bring to the game Selina Kyle and Miranda Tate/Talia al Ghul. We all know the evil intentions of Talia's plan, but we must also analyze the impact it has on Bruce. She is presented, by both Alfred and Lucius, as a "quite lovely" woman. These two man wants the best for Bruce. She represents the hope for a better life that Rachel was, but he is reluctant to accept it. It is more clearly displayed in the mansion scene, where Talia and Bruce enter by another door to the mansion, Talia finds the Rachel picture and asks who she is. Then as Talia approaches to kiss Bruce, there is an instant where Bruce pauses and reflects all of these, and then he kisses her. But all of these is a manipulative ruse to bring Bruce to his weakest point, she uses Rachel as an advantage, and among many other things, makes Bruce vulnerable.
And the star of the show is Selina Kyle. It is displayed in the first scene, when Selina steals Bruce fingerprints and his mother pearl necklace. He doesn't act annoyed or particularly mad. At the end, he is fascinated by this new woman who dared to go to these lenghts to steal at Wayne Manor. He is obviously attracted to her as well. As a good detective, he finds information about her, but also another thing. She is trying to begin a new life, a normal life. Something that Bruce deeply wanted too. And he sees good in her. It is a different thing from Rachel, because Selina is a broken person who has the potential for good. In a way, she is like Gotham City, a fractured place where there is still "good people". And Bruce/Batman arrival in Selina/Catwoman's life brings the good in her. They complement each other, and it shows in the witty banter's they have in the ballroom scene and when Bruce comes to visit her in the apartment scene. I love that in the end of the scene, Selina feels bad for Bruce predicament, and Bruce gallantly shrugs it off. They play each other well.
And while Bruce is fascinated by Selina, Selina is as well fascinated by Bruce. Though she shows appreciation for Batman, when she betrays him delivering him to Bane and learns that he is Bruce Wayne, there is pain in her eyes. She can't do nothing to help him, not yet at least. Bruce is also torn between these two great women. But as Talia's Miranda represent a part of his past that he has to overcome, Selina represents a unexpected new hope for a better life.
And the betrayal of Talia at the end of the film, hurts Bruce deeply. He was given a false hope, and it is truly a great scene. But he realizes that he has to move on. Selina arrives to save him, in more than one way. They have developed the beginning of a relationship, but it is Selina who save Bruce from his imposed destiny. She showed him that there is more to live. At the beginning of the film, Bruce is almost only waiting death, and Alfred is worried that he wants to die in his mission of Batman. When Batman flies over the ocean with the bomb, there is a nice moment when Batman reflects on all of this. Even though he can save himself, in my opinion, he may be thinking as well "This would be a good death…". It is great moment when we learn that he decided to save himself, he learned that he can confront and overcame all of the pain in his life, and that, despite his contrary belief, he can be happy.
So they both saved each other in many levels. It was great and one of the things I loved most about the film.
In short, Selina Kyle.