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.
Another plot could be set in an alternate universe where Harley Quinn and Nightwing are part of a resistance against an evil regime. Harley's chaotic nature and Nightwing's leadership skills combine to lead the charge. They have to overcome their differences and trust each other completely to succeed in their fight for freedom.
One plot idea could be that Spiderman and Harley Quinn team up to take on a common enemy in Gotham. Maybe a new villain emerges who has technology that can disrupt both of their cities, so they have to combine their skills. Another could be a story where Harley Quinn, being a bit of a wild card, accidentally gets transported to Spiderman's New York and they have to figure out how to get her back while also dealing with the chaos she causes.
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.
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 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.
One idea could be that they team up to take on a common enemy in Gotham. Maybe a new villain who is causing chaos in the city and the police can't handle it. They start off not trusting each other but as they fight side by side, they learn to respect and rely on one another.
Well, a great plot could involve Harley Quinn's chaotic nature clashing with Bane's more methodical and brute - force approach. For instance, they are forced to work together on a heist. Harley wants to do things her wild way while Bane is trying to stick to a plan. As they argue and work through their differences, they start to respect each other. Also, perhaps they find out that they both have a vendetta against the same corrupt Gotham official, which brings them closer.
One idea could be that Spider - Man and Harley Quinn team up to take on a common enemy in Gotham. Maybe a new villain who has a technology - based power that's affecting both New York and Gotham. Spider - Man's acrobatic skills and web - slinging combined with Harley Quinn's unpredictability would make for an exciting dynamic.
One idea could be that Harley Quinn and Joker have a baby, and the baby inherits their chaotic and unpredictable nature. Maybe the baby starts causing mayhem in Gotham from a very young age, and the other villains and heroes are all shocked and don't know how to deal with this new situation.
One idea could be that Harley Quinn tries to reform herself to be worthy of Batman's trust. Maybe she starts secretly helping Batman take down other villains in Gotham. Another could be a situation where they are forced to team up against a common, extremely powerful enemy, like a new supervillain who has a plan to destroy Gotham. And a third idea is that Harley Quinn has a change of heart about the Joker after seeing how Batman is constantly fighting for good, and she begins to see Batman in a new light, leading to a complex relationship between them.