American Psycho

Christian Bale really does the best job when it comes to presenting the bipolar complex of his character, specially with the almost instant contrast between the moment right before a killing and during it. The pure fact that Bateman reaches a tipping point in which he's unable to supress his desire to kill, just for there to be no consequence to anything that he does in the final act really got to me. The confusion that this creates reflects how the character must've felt so well.