Harley Quinn has an odd history. The character has become one of the most recognizable aspects of Batman’s mythos but did not originate from the comics. Rarely do characters that don’t exist in the source material get the kind of love that Harley Quinn did, and it seemed to have been the case for her initially as well.
Harley Quinn in Batman: The Animated Series | Warner Brothers

Back in 2017, Paul Dini sat down with Entertainment Weekly to talk about his character on her 25th anniversary, opening up about the thought process that went behind the character and what the fans thought about it initially. Turns out, the entire camp was split through the middle about the character of Harley Quinn.

Batman: The Animated Series had to win over the hardcore fans with Harley Quinn

Batman | Source: Batman: The Animated Series
Speaking with Entertainment Weekly, Harley Quinn co-creator Paul Dini revealed what the initial reaction to the character was like, and it seems it was not very different from how it would be received today. The benchmark, of course, remained the same: how are the hardcore fans going to take the change? Dini revealed:

Initially it was split. There was some “Oh, I hope she’s not around too much.” When you do an animated series and add characters who are not from the canon, you really have to win over the hardcore fans. Then there were some who thought she was cute and funny and wouldn’t mind seeing her come back.

But once we worked on her character a little bit, once we deepened and gave her that twisted attraction to the Joker, people were more interested. We showed she wasn’t just going to be a cartoon sidekick; she had some emotional investment in the Joker, and that’s what made her interesting.

Of course, Harley Quinn would go on to spawn a few titles of her own, completely distancing herself from the Joker’s influence in some iterations and becoming a bit of an LGBT icon. In multiple versions of the character, she even becomes a part of Batman’s inner circle, serving as his close confidant along with the likes of Robin, Nightwing, and the Justice League.

DC tried to recreate the success of Harley Quinn with another character

Punchline | DC Comics
Harley Quinn’s runaway success was not something that anyone could have foreseen. However, comic book fans could not get enough of the character, and DC was happy to oblige with more Harley Quinn content. However, there seemed to be a creative urge at the company to capture lightning in a bottle for a second time, and this probably is what led to the creation of Punchline, Joker’s rebound.

Punchline had a lot of things that Harley Quin did not. She was more sinister, more sadistic, and was simply all-around better at being Harley than Harley. This was the mistake that caused the character to feel alien to the viewers because it was obvious that Punchline was made as a gimmick, or a second Harley. Her costume was often described online as ‘cosplay friendly’, a feature that became associated with Harley in the wake of 2016’s Suicide Squad (and perhaps even before).

While this attempt to create a second Harley Quinn failed thoroughly, what needs to be remembered is that Harley was made a character in the show just because the creators wanted to have fun. There was no agenda behind Harley Quinn, other than the fact that she seemed like an be an interesting addition to the story.