Authors Note Before The Story Begins

On a cold brisk evening, (Y/N) attends her best friend's party. That best friend, of course, is Bruce Wayne. A little unexpected surprise shows up to crash the party, and she couldn't help but feel excited. Little did she know, the Joker was just as excited as her.
I do not own the characters, the only character that is made up is some of the goons, the reader. This will mostly be like The Dark Knight, but there will be some changes and additions to it.