Bane gets his strength from Venom as we know. But they threw his history of being born in the prison to serve his fathers sentence to Talia for no reason. Bane has never worked for someone else unless it served him in some way that benefited him the most. As a child, Bane also had numerous nightmares about a giant bat that haunted him until he broke Batmans back. The whole reason he came to Gotham was because he thought Batman was that bat and thought it was his destiny to defeat the bat and end his torment. And while Bane DID find out Batmans true identity, they did it out of order. Bane broke all the inmates out of Arkham and the passing weeks it took Batman to round them all up nonstop with no rest, it gave Bane enough time to find out who he was and Batman in his exhausted state left it all too easy to be beaten.