A plot idea could be that Deadpool is hired to assassinate Harley Quinn, but when he gets to know her, he changes his mind. He discovers that she's being framed for a crime she didn't commit. So they team up to find the real culprit. Deadpool uses his detective skills (which are a bit unorthodox) and Harley Quinn uses her connections in Gotham's underworld. As they dig deeper, they find out that it's all part of a larger conspiracy involving some big - name villains from both their universes.
One idea could be that they are both transported to an alternate dimension. In this dimension, all the rules are different. Deadpool's healing factor doesn't work as well, and Harley Quinn's usual weapons are useless. They have to rely on each other's skills and knowledge to find a way back home. Along the way, they meet strange versions of their friends and enemies, which adds to the hilarity and confusion.
One idea could be that Harley Quinn and Deadpool team up to take on a common enemy who has been causing chaos in both their worlds. They could start off as reluctant partners, with Harley being annoyed by Deadpool's constant chatter and Deadpool finding Harley's craziness a bit much at first. But as they fight side by side, they learn to appreciate each other's skills and form an unlikely friendship.
One plot idea could be that Deadpool and Harley Quinn team up to take on a common enemy, like a new super - villain in Gotham who has a connection to some of Deadpool's foes. They could start off not getting along because of their different personalities, Deadpool's fourth - wall - breaking and Harley's chaotic - cute nature. But as they face challenges together, they learn to work as a team and even become friends.
One idea could be that Deadpool and Harley Quinn team up to take on a common enemy, like a supervillain who's causing chaos in Gotham and also has a connection to one of Deadpool's foes. They could start off bickering because of their very different personalities but gradually learn to work together.
One idea could be that Harley Quinn and Deadpool team up to take on a common enemy in Gotham City. Maybe a new super - villain who has a plan to take over both the criminal underworld and the hero world. They could have a really chaotic and funny dynamic, with Harley's zany antics and Deadpool's fourth - wall - breaking humor.
A Deadpool and Harley Quinn crossover fanfiction might involve a love - hate relationship. They both have unique personalities. Deadpool could initially annoy Harley Quinn with his constant chatter, but then they find common ground in their disregard for the norm. They could end up on a quest for some strange object that has power over both their worlds, like a magical joker card that also gives Deadpool the ability to control time or something equally wacky.
One interesting plot twist might be that they end up falling in love. Given their unique personalities, this would be completely unexpected. They could try to have a normal relationship, but their criminal and chaotic tendencies keep getting in the way. Or perhaps Harley Quinn is actually an undercover agent sent to keep an eye on Deadpool, and when he finds out, he has to decide whether to trust her or not.
One idea could be that Harley Quinn somehow gets transported to the Marvel universe. Maybe she teams up with Deadpool. They both have a crazy and unpredictable nature, so their interactions would be really interesting. They could go on a wild adventure fighting against some common enemy like Doctor Doom who is trying to take over both their worlds or something.
One idea could be a story where Harley Quinn tries to break free from the Joker's control completely and starts her own life of crime without him. She could form her own gang and prove that she's more than just the Joker's sidekick.
Maybe Harley Quinn discovers some dark secret about Nightwing's past that she uses to blackmail him into helping her with a heist. But as they work together, they start to understand each other better. Nightwing realizes Harley isn't all bad and Harley sees that Nightwing has his own demons. In the end, they might even become friends or something more.
One idea could be Harley Quinn trying to reform herself and Batman being reluctantly drawn into helping her. Maybe she has some crucial information about a new villain in Gotham and in exchange for her safety and a chance at a new life, she offers to work with Batman.