Originally Posted by jonathancrane
The only way Harley Quinn would work in the universe Nolan constructed is if she was characterized as she was in Birds of Prey: as a Moriarty-like psychologist manipulating behind the scenes. The moment she starts behaving like a kid as she did in TAS, the illusion is broken.
But thats certainly an important trait of the character. You just need to develop it to fit this world. She is still dangerous, you just need to display that and combine it with her playful nature.