Why does Bane protect the girl?

I felt that while we assumed Bane was the child that escaped, it was because we knew his backstory included him being incarcerated as a child. I think that this is still the case and that the mirroring of his own circumstances was enough to want to protect Talia and help her be free. He was a man tortured by hope amongst criminals in the pit, he ended up caring only for Talia's happiness. Also, Talia's mother may have spoke to him about Ra's Al Ghul and promised to save him if he helps the child escape.

Bane protected Talia in the Pit because he could empathize the pain that he'd been going through since he was a child with her. He, like Talia, was "born in the dark, molded by it" and "didn't see the light until he was already a man". He wanted to preserve the innocence that he lost during his childhood by protecting Talia. Bane is like a second father to her.

The motivation for the League of Shadows' acts of seemingly-random destruction was stated in Batman Begins as a kind of purification of society once it had become too corrupt. Bruce Wayne's point of difference with the League was not about ends, but means. The members of the League of Shadows see themselves as good people willing to do what it takes to purify humanity.

There is therefore no contradiction in Bane being compassionate and self-sacrificing and joining the League. If he was just out for himself, the League would have probably had no interest in him.

The League tried to harness Bruce's rage, but succeeded in twisting Bane's compassion.

It's stated in the move that the "protector" saves the child due to a feeling that the innocence of the child needs to be preserved. In all likelyhood, Bane could sympathize with Talia, having himself grown up in prison.

This is actually explained in the prisoner's story, as he tells it to Bruce:

The legend is that there was a mercenary who worked for the local warlord. He fell in love with warlord's daughter. They were married in secret.

When the warlord found out, the mercenary was condemned to this pit. But then he exiled him instead. The mercenary understood that was the daughter who had secured his release.

But what he could not know was the true price of his freedom. She took his place in the pit. And she was with a child. The mercenary's child.

Innocence cannot flower underground. It was to be stamped out.

One day, the doctor forgot the lock the cell. But the child had a friend. A protector who showed the other that this innocence was their redemption, it was to be priced.

The mother was not so lucky.

This is Bane's prison now. He wouldn't want the story told.

Saving this child was the one good (actually, the only significant) thing that Bane could do in his life. He had no prospect of ever leaving the Pit or doing anything remotely significant.

The accepted answer mentions that Talia's mother may have told him about Ra's Al Ghul and that he might have expected to be rescued as a reward. I think this is deeply wrong and maybe even offensive to his motives. A little girl, who has never even seen the outside of the Pit, who had no resources whatsoever, whose father didn't even know that she existed,... her mere survival would be a hard gamble. Also, his own survival of the riot is a minor miracle in itself, and he must have been aware that he is not likely to survive helping Talia. So, expecting any kind of reward is wrong and I strongly believe that his action was completely pure and exclusively focused on the salvation of that one child.

At the end of the movie, when Talia says her goodbyes to Bane, he cries, as he knows it's the last he sees of her, and that both of them are to be dead soon. Obviously, he has huge empathy for her... and only for her.

PShin wrote that "Bane is like a second father to her". This is close, but I think still incorrect. Bane is the father to her (not biological, but in emotional, protective, and every other way) and he sees her as his true daughter. I assume he took her under his protection "as his redemption", and grew very fond of her through the years he cared for her in the Pit.

After all, it is not hard to see that an innocent child was his only (metaphorical) light in the long years he spent there. Hence, his contempt for all but her, and huge devotion to her (and only her). I also think that her feelings are quite reciprocal, and for the quite similar reasons.

I think initially Bane's motivations aren't about evil. He saw the similarity between him and Talia growing up in the pit so he helped her to escape.

After helping Talia and being attacked by the prisoners, his motives changed as he was in constant pain. This pain lead him down the path of evil and eventually onto becoming "Gotham's Reckoning".

I figured that Miranda was with Bane but was dissapointed that he ended up being just a fool in love. But when you think about it it does make sense . Bane was a purely rational and sane mercenary, so once it was established his main motive was not money then it had to be something else, LOS? but in reality he was a mercenary so doubt he shared their agenda n also they kicked him out before, so if its not money or ideology then it can only be love.

Maybe because Bane is not evil by nature, The Pit made him ruthless. By birth Bane may be like Bruce, good and kind. Thats why when all the prisoners attacked the young innocent Talia without mercy, Bane is the only one, among the evil prisoners, showed compassion and protected. he is willing to risk himself for the safety of the girl. I also doubt that thats the reason why Ras excomunicate Bane, because he shows compassion to people , the same morality Bruce showed in batman begins that made Ras angry( The scene where Bruce refused to kill a theif ras captured). Maybe Bane is similiar. After all banes attack to Gotham was only a loyalty or to settle a dept he owed to both Talia and Ra`s who helped him from the horrible Pit