Bruce has very expressive eyebrows. Even tho he mastered the blank poker face, he sometimes likes to express his emotions through his eyebrows. Its amazing feat, according to his kids.
But when in the batman suit, his eyebrows are useless so he employees his lips to express his emotions without saying anything. And just like his brows, it is also very expressive.
His usual neutral lips is the default position. Straight, blank, not saying much.
The slight down turn, not exactly frown, but close to it is when its 2 am and hes blaming the batcomputer for his problems.
A full on downward lip is when an unexpected alien attack or joke decides to escape again. That one lasts the whole ordeal.
A slight upturn of the corner of the upper lip, while the other goes slightly down, which is basically disgust, when someone in the league says a stupid thing or suggests a stupid plan.
Two lips sucked inwards, like he tasted a lemon, is when he sees his batkids coming to him with the usual guilty face, meaning something happened.
The slight open mouth, not the usual gape but something close, when jason comes home with a smug smirk and suspicion blood stains.
Very more commen than not snarl comes when something is not going his way, which happens a lot with the league.
A slight, very unnoticeable, upturn of his lips, when Alfred presents him his favorite, diabetic, too much whipped cream desert after a 3 days no sleep marathon.
The small proud smile, rare but genuine, when he sees his kids getting along and being kids.
The lower lip bite when clark is in the farm sweaty and shirtless.
The full on open mouth to scream when clark hits the right spot.
