From the production notes of TDKR: link.

I don't like Christian Bale much, as an actor, I mean - the same goes for Anne Hathaway, actually - but this made me go all "Aww..." It's so sweet.

It happened in the midst of a massive crowd scene on Wall Street in Manhattan, during a fight sequence between their two characters.
“It was the first time I ever heard Christian say he was tired,” Hardy remembers. “I was watching him for however many months getting beaten up and wet and cold, and he never said anything. Inside, I was dying, but I was thinking, ‘This can’t bother me because he’s not bothered.’ But on Wall Street, he just turned and said, ‘You know what? I’m exhausted.’ I said, ‘Me too.’”
“We stopped the fight and started hugging each other,” Bale adds.
I don't like Christian Bale much, as an actor, I mean - the same goes for Anne Hathaway, actually - but this made me go all "Aww..." It's so sweet.
