You see we all know the joker simply for his theatrical cartoony ways of dealing of things but with the Dark Knight's Joker, as he said he's "a man of simple taste" gunpowder, dynamite, and firearms will do it for him, whitch would leave you believing that he might have had special training with it A.K.A military training, and if he were in the military there is a good chance he was on the field and was sent home with post traumatic stress disorder (PTSD) causing him to become very paranoid and eventually losing his mind and becoming the anarchy seeking maniac we know.
But then again there's the, "why so serious?", monologue where he claims his father caused his facial scarring. Which is also a good hint to maybe where his persona came from because childhood trauma has been known to cause schizophrenia, paranoia, and sociopathic actions and behavior, in which could have caused him to become who he is.
Although if you think about it none of this might even be true. The Dark Knight Joker is a psychopath of his own taste, he asks for death, like in the scene where he stands in the street yelling for batman to hit him, maybe just he is a psychopathic man who lost his ability to feel pain and emotion, pointing to the amount of beating he can take at a time without stop and the facial scarring, he more than likely did it himself to make up for the fact that he doesn't care anymore. He tries to use humorist senses and sarcasm to extend for the fact that he has no REAL emotion, why else does absolutely nothing get on his nerves?
The joker is nothing more than a mentally insane man with scars that show that he will use a smile to his advantage. He does not care whether or not he succeeds or not or whether he dies or not he just will do things without a care in the world. His only goal is to destroy order and cause anarchy and mayhem.
Tell me your opinion on what you think of what i take who the joker is.