One idea could be a crossover where the Bat family teams up with the Teen Titans. They could combine their skills to take on a powerful new villain that neither group could defeat alone. For example, Batman's detective skills and Robin's agility along with the Titans' unique powers would make for an exciting story.
A time - travel based bat family crossover fanfiction could also be great. The Bat family members could be sent back in time to when Gotham was first founded. They'd have to deal with the primitive conditions while also trying to find a way back to their own time, all while facing some of Gotham's earliest threats.
A Bat Family OC fanfiction could focus on an OC who is an artist. They use their art as a form of communication and also as a way to leave clues for the Bat Family. This OC might be in the middle of a mystery that involves some of Gotham's art underworld. The Bat Family has to figure out how this OC fits into the bigger picture. It could also be an OC who is a street kid that Batman takes under his wing. This kid has a natural talent for acrobatics and stealth, and slowly becomes an important part of the Bat Family.
One idea could be exploring the relationship between Batman and Robin in a different light. Maybe Robin has to take on Batman's role temporarily when Batman is injured. Another idea is a story about Batgirl's early days of training and how she overcame difficulties.
One idea could be that the bat family encounters a supernatural force that gives them new powers. For example, they might come across a magical amulet that allows them to fly without their gadgets for a short time.
One interesting concept could be exploring alternate universes where different members of the bat family have different roles or powers. For example, a world where Robin is the main vigilante instead of Batman. Another concept might be team - ups that don't usually happen in the main canon, like Batgirl and Nightwing working on a mission in a completely different city. It could also involve crossovers with other DC families in a fanfic, such as the Flash family.
A third idea is to have a time - travel plot where members of the Bat Family in Young Justice go back in time to a crucial moment in Batman's early days as a vigilante. They could witness events that shaped Batman into the hero he is and learn valuable lessons from it. Along the way, they might also accidentally change something in the past, creating a whole new set of challenges to fix in the present.
Some interesting concepts in bat family fanfiction involve exploring the backstories of the less - known members. For instance, delving deeper into the story of Batgirl and how she came to be part of the family. There are also fanfictions that focus on the family's vacations or downtime, which is a fun way to show a different side of these usually serious crime - fighters. It gives a more human touch to the Bat family.
One idea could be that the Bat family is investigating a strange series of crimes in Gotham. Meanwhile, the Young Justice team stumbles upon a lead that takes them to Gotham as well. They initially clash due to different methods of operation. Batman tries to keep his family in line while also dealing with the young, headstrong heroes of Young Justice.
One idea could be a story where the Bat family decides to have a game night with a twist. They play a version of 'hide and seek' throughout Gotham City, using their skills and gadgets. It would be filled with action as they chase each other around the rooftops and dark alleys.
One idea could be a story where a new student arrives at the school who is secretly a member of the bat family. They have to balance their normal school life with their superhero duties. For example, they might be late for class because they were out stopping a crime the night before.
The little bat could discover a hidden cave filled with ancient bat artifacts. It then has to protect this cave from other animals who might want to take over or destroy it. This could involve making alliances with other bats and using its wits to outsmart the invaders.