One possible plot could be that Batman and Catwoman have a child who discovers their parents' secret identities by accident. The child might then try to use their own skills, a combination of Batman's detective skills and Catwoman's agility, to help their parents fight a new villain in Gotham.
Perhaps the story could focus on the challenges of raising a child while being superheroes. Batman and Catwoman might have to balance their nightly crime - fighting with taking care of their child. Their child could also start to show signs of having special abilities, like super - strength or enhanced intelligence, and they have to figure out how to help the child control and use these powers for good.
In the fanfiction, their child could be kidnapped by an old enemy of Batman or Catwoman. This forces the two to work together in a new way, not just as partners in crime - fighting, but as parents desperate to save their child. They might have to use all their resources and call in favors from other superheroes or villains-turned - allies to rescue their offspring.
Ra's al Ghul could also be a main villain. He might see the child of Batman and Catwoman as a potential weapon or a threat to his plans for Gotham. He could try to either recruit the child to his side or eliminate them, which would put Batman and Catwoman in a difficult position as they fight to protect their family from Ra's al Ghul's devious schemes.
One scenario in the fanfiction could be that Batman gets jealous when he sees Catwoman flirting with a rich businessman during one of her heists. He might start to question her motives and their relationship. This jealousy could cause him to act out of character, perhaps being more aggressive or possessive towards Catwoman than he normally would be. And Catwoman, being the independent character she is, would not take kindly to this sudden change in Batman's behavior, leading to a rift between them that would be interesting to explore in the story.
A possible plot could be that Catwoman discovers she's pregnant. She then has to decide whether to tell Batman or not. She might be worried about how he'll react, considering their different lifestyles. Eventually, she tells him, and they start to plan for the future. They could face challenges from their enemies who might see the baby as a weakness or a target.
In a different take, the wedding could be a way to unite the two sides of Gotham. Batman and Catwoman, after years of their on - again - off - again relationship, realize that their union could bring peace. They hold a public wedding in Gotham Square, with the entire city watching. However, Joker tries to ruin it by spreading chaos. But Batman and Catwoman, now as a couple, use their combined skills and the help of the citizens who have come to support them to stop the Joker and start their new life together as symbols of a new, united Gotham.
A way to develop their relationship in this type of fanfiction is through joint parenting. They might have different approaches to raising their kids. Batman could be very strict about discipline and training, while Catwoman might be more lenient and focus on teaching the kids about the importance of freedom. Through these differences, they learn to understand each other better and grow closer as a couple. Also, they could face external threats to their family which forces them to rely on each other more, strengthening their bond.
She might be very surprised at first. After all, Batman is not one to show his emotions so openly. But then she would likely be overjoyed. She has deep feelings for Batman too, and this proposal would be a confirmation of their complex relationship.
One idea could be a story where Batman and Catwoman team up to take on a new, more powerful villain in Arkham. Maybe this villain has the ability to control the minds of the inmates, creating chaos. They'd have to use their unique skills, Batman's detective work and combat abilities, and Catwoman's agility and thieving expertise to stop the threat.
One idea could be that Batman and Catwoman have a daughter who discovers her parents' secret identities. She could struggle with the duality of their world and try to find her own place in it. Maybe she has her own unique set of skills that combine elements of both Batman and Catwoman.
One plot idea could be that Catwoman is on a heist and Batman tries to stop her as usual, but during the encounter, they share a moment where they realize their mutual attraction. They start secretly meeting up, away from the chaos of Gotham's crime world, and gradually fall in love. Another idea is that they are forced to work together to take down a common enemy much bigger than their usual foes. In the process, they see different sides of each other and their relationship deepens.
Well, perhaps a plot where Catwoman is injured during one of her heists and Batman finds her. Instead of turning her in, he takes her to his secret lair to nurse her back to health. As she recovers, they start to have long conversations about their lives and motives. This deepens their connection and eventually leads to a romantic relationship full of tension and passion, with Catwoman teasing Batman and him trying to keep his cool while being drawn to her allure.