Perhaps in the fanfic, Robin is captured by Harley Quinn. Batman arrives to save him. Harley Quinn taunts Batman, saying he's too late and that she's already turned Robin to her side. But Robin reveals it was all a ruse to get close to Harley and find out the Joker's next big plan. The scene could be filled with Harley's wild laughter and Batman's stoic determination.
A plot could involve Robin being kidnapped by one of Harley Quinn's old associates who has a vendetta against her. Batman and Harley Quinn then have to work together to rescue Robin. During the rescue mission, Harley Quinn starts to see Batman in a new light and realizes that his way of fighting crime might be more noble than she initially thought. Meanwhile, Robin, while being held captive, manages to outwit some of the captors, setting up an exciting climax when Batman and Harley arrive.
The relationship can be complex. Batman could be seen as the stern mentor figure to Robin, while Harley Quinn is the wild card. Robin might be initially afraid of Harley but also a bit intrigued. For example, Harley could mock Robin for following Batman so blindly, which angers Batman. Robin might then stand up to Harley, showing his growth and loyalty to Batman.
Well, perhaps Harley Quinn is kidnapped by a powerful criminal organization that wants to use her knowledge of the Joker's operations. Batman gets wind of it and sets out to rescue her. During the rescue, they might have some interesting exchanges. Harley could be initially distrustful of Batman, but as he battles through the bad guys to get to her, she realizes he's not as bad as she thought. It could also be a setup by the Joker to test Batman, and Batman has to outwit both the Joker and the kidnappers to save Harley Quinn.
One possible plot could be that Harley Quinn discovers she's pregnant and tries to hide it from the Joker, fearing his reaction. Meanwhile, Batman somehow gets wind of it and feels a sense of responsibility to protect her, not just for the baby's sake but also because he realizes Harley is in a very vulnerable state.
A possible plot could be that Harley Quinn's sister is an undercover agent sent to infiltrate the criminal underworld of Gotham. She ends up getting involved with Harley and the Joker. As she gets closer to her sister, she realizes that Harley is more than just a crazy villain. She then tries to find a way to get Harley out of the criminal life while also dealing with Batman's suspicions of her true motives.
Fanfics about Robin and Harley Quinn with a 'lemon' aspect can be a double - edged sword. On one hand, they can add new dimensions to the characters that we don't see in the official stories. For example, exploring how Robin's sense of justice might clash or blend with Harley Quinn's chaotic nature in a more intimate setting. On the other hand, they can also attract a lot of criticism if not handled well, especially when it comes to staying true to the core of the characters and the overall tone of the original works.
In a fanfic, the relationship between Batman and Robin is typically one of mentor and mentee. Batman is the experienced, brooding hero who guides Robin. Harley Quinn's relationship with them is more complex. She might start as an adversary to both, but as the story progresses, she could develop a begrudging respect for Batman's code and start to see Robin as an innocent in need of protection. Batman, on the other hand, would be initially very distrustful of Harley, but over time might see her potential for good. Robin would be curious about Harley, and his more open - minded nature could be the bridge between Batman and Harley's relationship.
In many fanfics, Harley Quinn realizing Bruce is Batman can lead to some really interesting plot developments. Maybe she discovers it by accident, like seeing Bruce act in a way that's too similar to Batman's mannerisms. It could also be that she pieces it together from some clues that others have overlooked. This realization might make her re - evaluate her relationship with both Bruce and Batman, and it could create a whole new dynamic in the story.
One possible aspect of a Batman and Harley Quinn fanfic could be exploring their relationship in a different light. Maybe in a world where Harley Quinn is trying to break free from her villainous past and Batman is reluctantly helping her. It could be an interesting dynamic as they both have complex personalities.
A Batman and Harley Quinn fanfic could show them forming an alliance against a greater threat. For instance, a new super - villain emerges who is more dangerous than the Joker. Batman realizes he needs Harley's knowledge of the criminal underworld to stop this new foe.