This movie evokes a mysterious laugh from the darkest recess of our soul.
For Arthur it is probably a case of emotional rewiring , in a way that the dark psychotic responses becoming Second Nature, and over time reducing his pysche and current personality.
The people of Gotham too are slowly sucked into the vortex of disgruntled protests, culminating in the death if Thomas Wayne , who is the symbolic edifice of all that they are not.
Worth a delve; into the dark recess of our mundane mind.