The Dark Knight (2008) demonstrates Christopher Nolan's intentionality in staging. The film meditates on faces and masks. Harvey Dent is "the face of Gotham's future" and becomes Two-Face. The Joker can't be identified through facial recognition. Batman hides behind a mask.

The Joker is based on the Commedia dell' arte character Arlecchino, as depicted in the Joker calling cards he leaves and taken from medieval passion plays. His role was always as a trickster meant to thwart the "White Knight" which Dent is referred to in the film.

Passion plays were performed in the Catholic Church in Italian and form the basis of modern day stage plays. Performed within the floor plan depicting a cross villains entered to the audiences left, or "sinistra", which is why Joker holds his mask in his left hand.

*Right hand but to our left, the audiences sinistra.