A really interesting plot could be that there's a reality - warping villain who mixes the worlds of Gotham and Metropolis. Superman finds himself in a strange Gotham - like Metropolis and Catwoman is the only one who can help him navigate the new, darker rules of the city. As they work together, they start to see the good in each other's worlds and form an unexpected bond.
Maybe there's a plot where a powerful alien force arrives on Earth and starts causing chaos. Superman is having a hard time dealing with it alone as the aliens have some new form of kryptonite - like energy. Catwoman, with her stealth and street - smart skills, discovers a way to neutralize the kryptonite - like effect, and they join forces to save the day.
One plot idea could be that Superman and Catwoman are forced to team up against a common enemy, like a powerful alien or a supervillain who is threatening both Gotham and Metropolis. During their partnership, they start to understand each other's motives and develop an unexpected bond.
A possible plot could be that Lex Luthor teams up with some of Catwoman's foes to frame her for a major crime. Superman is initially sent to capture her but as he digs deeper, he realizes she's been set up. So he decides to help her clear her name. During this process, they have to hide from both the law and their enemies. In the close quarters and the shared danger, they form an unexpected bond.
One idea could be that Catwoman steals a valuable item and Superman is tasked with retrieving it. But as he chases her, he realizes she has a noble reason for the theft, like helping the poor in Gotham. So, instead of simply arresting her, he decides to help her find a legal way to achieve her goal.
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.
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.
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 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.
In this fanfiction, it could be interesting if Catwoman discovers a secret about the Arkham Knight that Batman has overlooked. She could use this knowledge to her advantage, either to make a deal with the Arkham Knight or to help Batman. For example, she might find out that the Arkham Knight has a weakness related to a certain location in Gotham that was important to his past. Catwoman could then lead Batman there to take down the Arkham Knight.
Perhaps in the Young Justice universe, Catwoman discovers a secret about Batman's past that puts her in a moral dilemma. She could either use this information to her advantage or help him keep it hidden. As they interact more because of this, feelings start to develop between them that they didn't expect. They have to navigate their relationship while also dealing with the threats that Young Justice faces.
One idea could be that Robin is on a solo mission in Gotham and crosses paths with Catwoman. She initially tries to mislead him, but he sees through her tricks. They end up teaming up briefly to take down a mutual enemy who is stealing valuable artifacts from both the Batcave and Catwoman's hideouts.