Perhaps a story where Bruce Wayne is at the police academy undercover to investigate a series of crimes that seem to be linked to someone in the academy. He has to balance his normal life as Bruce, his training at the academy, and his secret investigation. He could make friends with some cadets who end up helping him in his mission, or he could be in a situation where he has to choose between following the academy rules and doing what he believes is right to solve the case.
One possible storyline could be that Bruce Wayne gets injured during a fight with a new and powerful villain in Gotham. He has to rely on his allies like Alfred and the Bat - family more than ever to keep Gotham safe while he recovers. Another could be that he gets injured in his civilian identity, and has to hide his true nature even more carefully to avoid suspicion as he heals.
One storyline could be that Harry, after the events in the wizarding world, decides to take a break and travels to Gotham. There he meets Bruce, and they end up teaming up to take on a new threat that combines magic and Gotham's usual criminal element. Maybe a villain who has somehow gotten hold of a powerful magical artifact and is using it to wreak havoc in the city.
A possible storyline could be that Percy is on a quest and gets lost in a different dimension which happens to be Gotham. Bruce Wayne, as Batman, finds him and initially suspects him to be a threat. But as they interact, they discover some similarities in their abilities and goals. They then start to dig deeper and find out they are related through a long - lost family connection that dates back to ancient times when the gods had some influence on the early human civilizations.
One possible storyline is a competition between them. They could bet on who can solve a particular global threat faster. Bruce would use his detective skills and resources in Gotham, while Tony would rely on his Stark tech. Another could be that they get framed for a crime together and have to work together to clear their names while also finding the real culprit.
Another storyline could be set during a gala in Gotham. Bruce's girl best friend gets into trouble with some of the seedy characters at the event. Bruce, as Batman, has to save her without revealing his identity to her. This would lead to a lot of internal conflict for Bruce and some interesting interactions between them afterwards.
Bruce Wayne's presence would likely bring a sense of discipline and high standards. His skills and knowledge are far beyond the average cadet, so he could inspire others to strive for more. For example, in physical training, he'd set new records and make others work harder. Also, his moral compass would influence the academy's culture, making it more about true justice rather than just following orders.
One possible storyline could be exploring the immediate aftermath of Bruce's death. How does Terry McGinnis handle the loss? Another could be flashbacks to Bruce's final days, showing his last words of wisdom to Terry.
One interesting storyline could be about a new recruit at the police academy who has a unique skill, like being able to read people's micro - expressions. This recruit uses this skill to solve a mystery within the academy that involves missing equipment. Another could be a time - travel story where a modern - day cadet is sent back to the early days of the academy and has to adapt to the old - fashioned training methods while also introducing some new ideas.
A really interesting Young Bruce Wayne and Alfred fanfiction storyline could be one where Alfred has a secret past as a spy. This could add a whole new layer to their relationship as he teaches Bruce some of his spy skills. It would be exciting to see Bruce adapt these skills in his crime - fighting later on.
One interesting storyline could be Callahan taking on a mentoring role for a new recruit at the police academy. He could pass on his unique skills and wisdom, leading to a series of comical and heartwarming interactions.