The Joker tells two different stories of how he got his scars in THE DARK KNIGHT. Why?
The first version is told to Gambol, the crime boss:
Wanna know how I got these scars? My father was a drinker and a fiend. And one night he goes off crazier than usual. Mommy gets the kitchen knife to defend herself. He doesn’t like that. Not. One. Bit. So – me watching – he takes the knife to her, laughing while he does it! Turns to me, and he says, “Why so serious, son?” Comes at me with the knife… “Why so serious?” He sticks the blade in my mouth… “Let’s put a smile on that face!” And… why so serious?
The second version is told to Rachel:
Oh, you look nervous. Is it the scars? Wanna know how I got ‘em? C’mere, look at me. So, I had a wife, who was beautiful…like you, who tells me I worry too much, who tells me I oughta smile more, who gambles and gets in deep with the sharks… Hey. One day they carve her face. And we got no money for surgeries. She can’t take it. I just want to see her smile again. Hmm? I just wanted to let her know that I don’t care about the scars. So, I stick a razor in my mouth and do this… to myself. And you know what? She can’t stand the sight of me! She leaves! Now I see the funny side. Now, I’m always smiling!
Why does the Joker tell two different, contradicting stories?
The most superficial interpretation is: the Joker is insane. He is so mentally ill he is incapable of being honest or consistent even with himself. So, the stories reflect Joker’s mental turmoil.