Although ‘The Dark Knight’ offered a narrative into Gotham city from the eyes of the protagonist Batman, there are many peculiarities about the "antagonist" of Joker that catch the eye- the most prominent being scars on his face forming a ‘permanent’ smile. With the disfigurement being hard to ignore, different stories emerged across different adaptations regarding the origins of the scars.
One story being that his abusive father, in a rage fit, carved these marks into his skin while repeating the ever-famous line ‘Why so serious?’, which became the catchphrase of the Joker himself. The second story proposed that Joker’s wife found herself in trouble with gambling sharks who ‘carved her face’ and he disfigured himself in this way to show her he didn’t care about her appearance, which however, led to their separation as his wife could not bear to look at him, triggering his villainous arc. Another adaptation marks him with a perpetual grin after a tragic accident at Ace Chemicals, his side job in the storyline, that alters his skin color, hair and leaves him with this eternal defacement. In others, the character's enigma is further enhanced by the purposeful ambiguousness of its origins.
This unique feature not only represents his anarchist outlook but also functions as a graphic depiction of the character's lack of “rationality” and abidance with social norms. This also creates a stark contrast to Batman’s serious demeanor, enhancing the chaos versus order theme in each movie, making his smile one of the most important concepts needed to understand his disposition.
The origins of the Joker's smile scars are depicted in shades of ambiguity and uncertainty- with origins ranging from hostile childhood relationships to gruesome catastrophes - allowing us to sympathize with the deranged legacy of a figure who brings into being one of fictions most liked villains.