For almost all of Harley Quinn's entire existence, she's been a big thorn in the side of Batman. Gotham's protector has had to deal with Quinn and the Joker's criminal plans and actions for a while, but things are about to change. Quinn will team up with the Caped Crusader as his new sidekick in an upcoming arc of DC's Batman.

In the past few years, Harley Quinn has become more of a heroic character, across almost all mainstream interpretations. While she's not a full-blown 'good guy,' Quinn has definitely become more of an antihero, whose break-up with the Joker has allowed her to develop further as a character. It's what makes Harley's DC Universe animated series so good, which means joining forces with Batman as she's set to do in 2020 makes a lot of sense, even if it seems bizarre at first glance.

RELATED: Batman & Harley Quinn May Finally Be Headed For Romance

In the upcoming solicits for Batman #91 by James Tynion IV and Jorge Jimenez, Quinn will be teaming up with Batman against a series of villains including the Penguin, the Ridler, and an all-new bad guy called 'The Designer.'

To save Gotham City, Catwoman will have to commit the greatest heist in the city’s history! But hot on her trail are the Penguin, the Riddler, a horde of assassins, and the master criminal called the Designer! And the most dangerous person standing in her way is the man she’s trying to save: Batman. And what complications will his arise from his new sidekick, Harley Quinn?

It's not the first time Quinn served as Batman's new sidekick. In Harley Quinn #58, Quinn is accused of a crime she didn't commit and teams up with Batman to prove her innocence. The two butt heads in the issue, with Harley even handcuffing herself to Batman. But after the case is solved, Batman acknowledges her as a good person. However, the story ends up being part of a cosmic trial by the Tamaranean Mirand'r. Tynion IV's story will most likely be a much more grounded version of Harley Quinn and Batman - not involving cosmic entities, and the kind of heightened ridiculousness of Harley's current ongoing series. When the arc comes around, Tynion will be six issues deep in his new Batman run.

It's not yet known what ultimately brings Batman and Quinn together. But, the two opposites make a fantastic pairing. Batman's cold, calculated attitude mixed with Harley's unpredictable, hit-first, ask questions later persona is going to be extremely fun. Still, there are a ton of questions that will need to be answered. How exactly does Harley Quinn end up as Batman's sidekick? Does Robin approve? Will the two share their opinions on the Joker? We'll find out when Batman #91 hits store shelves on March 18, 2020.

NEXT: DC’s Harley Quinn Show Shows Why Batman Villains Are Ridiculous