Brooding, pragmatic, and paranoid to the point of trusting no-one, it's inevitable that every once in a while the Dark Knight has to defeat his fellow superheroes.
As much as this is generally due to said other hero being brainwashed or possessed, it's not uncommon for him to fight and beat an entirely lucid hero, for reasons that vary from 'reasonable' to 'because he can'.
This second reason is in no small part motivated by the fact that Batman has created plans to defeat literally everyone he has ever met, meaning that when he does end up having to fight one of his allies, he does so with a pre-written 'How To' guide hidden up his sleeve, balancing out the fact he's going up against some of Earth's most powerful individuals.
And this preparation is fortunate, as Batman also appears to be the hero most likely to end up in a fight with other superheroes, with everyone from Huntress to Superman ending up against Gotham's protector at some point or another. You'd be easily forgiven for thinking the Dark Knight had accidentally joined some kind of superhero Fight Club - and given he's fought Superman over ten times in the main DC universe, you'd almost be right.