When it comes to Harley ... Reeve's Batman universe, which is not part of the DCU at the time of this writing. However, if the DCU does want to go a different direction with Harely Quinn, Joker ...

Fans may be surprised to learn that Harley Quinn's first costume in comics was a complete knock-off of Joker's design; luckily, it was short-lived. In Batman: Harley Quinn #1, Harley and Batman ...