The reason I like them the most is that the two people "like two lunatics locked in the same mental hospital", rather than superheroes and high-IQ criminals. They are like the front and back of darkness. Batman is extremely rational and restrained. Joker is extremely crazy after rational distortion. He is obsessed with Batman and wants him to break his restraint and cling to "Why don't you laugh". Batman disguised and restrained himself in the dark to protect Gotham City. Joker saw through Batman's pain and past. He tried his best to tear off his mask again and again. At the end of the movie, the scene where Batman and Joker laugh together, I was shocked.
The sins in life make Joker, Joker makes Batman
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