One interesting plot could be the daughter's struggle to live up to Batman's legacy while also forging her own identity. She might face villains who target her because of her relation to Batman.
One interesting plot could be the sons teaming up to solve a mystery that Batman himself has trouble with. They might use their unique skillsets, which are different from Batman's, to approach the case from a new angle.
In some fanfictions, their daughter might face a great threat to the wizarding world. Maybe a new dark wizard emerges, and she has to step up and use her combined heritage from Harry and Hermione, as well as her own skills and courage, to defeat the enemy. She might struggle with the pressure at first but eventually grow into a great hero.
One interesting plot could be her discovery of her father's past. Maybe she stumbles upon some old artifacts or memories that lead her to understand the sacrifices he made. For example, she might find his old Death Eater's mark and then try to piece together what it means for her family's history.
In some fanfictions, her plot could revolve around time - travel. She might accidentally travel back in time and meet her father when he was a student. This would give her a chance to see a different side of him and understand his choices better. She could also try to change some events in the past to make a better future. However, this would bring a lot of consequences and she would have to deal with the butterfly effect in the wizarding world.
One interesting plot could be Bella growing up in the Cullen family with Carlisle as her father. She might inherit some special vampire traits early on and have to deal with the unique challenges that come with it, like hiding her abilities from humans. Another plot could involve her relationship with the other Cullens, perhaps having a different dynamic with Edward as her 'brother' which changes the whole Twilight love story.
Another plot could involve her struggle to fit in with normal society while having this extraordinary phantom - related background. She may face discrimination or misunderstanding from others, but in the end, she manages to find a group of people who accept her for who she is.
One idea could be that Batman has to protect his baby daughter from his rogues gallery who see her as a way to get to him. For example, the Joker might try to kidnap her in a really twisted plan.
One interesting plot could be Batman and Sherlock teaming up to solve a mystery that involves both Gotham and London. Maybe a criminal organization is operating in both cities and they have to combine their skills. Batman's combat and detective skills in Gotham's dark alleys and Sherlock's deductive reasoning in London's Victorian - like settings would make for an exciting story.
One interesting plot could be Catwoman in the 'Batman Beyond' universe stealing a high - tech item that has the potential to disrupt the new Gotham's power grid. Batman Beyond then has to track her down, leading to a series of high - speed chases across the city's skyline. Another plot might involve Catwoman forming an unlikely alliance with Batman Beyond to take down a new criminal organization that is using advanced technology for illegal activities. And perhaps a plot where Catwoman discovers a secret about Batman Beyond's identity and uses it to her advantage in a heist.
One interesting plot could be that Batman and Lois Lane team up to solve a mystery that involves both Gotham and Metropolis. Maybe a new villain is creating chaos in both cities, and their combined skills are needed to stop it. Batman's detective skills and Lois's journalistic instincts would make for an exciting adventure.