The terrifying costume of the joker the iconic extra lipstick smile that no other Villain can ever replicate. The Joker’s face paint is patchy and his clothes look weathered. But that’s what really added to making him feel more Real.
The Joker didn’t have any Agenda to follow, The Joker did what he did because he liked it, and though he’s incredibly destructive, he does all of it for “fun”, for the simple reason that it gave him pleasure. That makes him so unique amongst villains.
He is not afraid of dying as he knows that Batman can not kill him so he puts his life on the line because he knows Batman won’t be able to change what he does.
The Joker Understands the Batman on an Emotional and Personal level. He gets into his mind and toys around with Batman’s darkest secrets. On the whole Joker doesn’t mind getting killed in the process.
The Joker is not afraid of batman which is a problem because his arguably most important power is of intimidation which does not affect the joker which adds a phycological scar on Batman.