The development of Damian is crucial. We should see him grow from a somewhat brash and angry kid to a more empathetic and team - player. Nightwing can expose him to different cultures and people in the fanfiction. This could lead to Damian having a broader perspective and better understanding of the world around him.
One interesting fanfiction could be where Nightwing takes on the role of Damian's mentor in a very strict yet loving way. He teaches Damian not just combat skills but also about morality and friendship. In this story, they might go on adventures together, facing villains that force Damian to grow under Nightwing's guidance.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of DC - related fanfictions, and you're likely to find many 'nightwing meets damian' ones there. Just use the search function and type in the relevant keywords.
There's a fanfiction called 'Nightwing and Damian: A New Alliance'. In this story, Nightwing takes Damian under his wing to teach him some of the more subtle aspects of crime - fighting. It has some really cool action scenes where they work together in perfect sync. Also, 'Damian's Redemption through Nightwing' is a good one. It delves into Damian's inner turmoil and how Nightwing helps him find a better path.
One plot idea could be Nightwing teaching them his unique combat skills. He could have a special training session where he combines his acrobatic fighting style with elements from each of their own combat preferences. For example, incorporating Jason's more brute force when necessary, Tim's strategic thinking, and Damian's precision. Another idea is Nightwing helping them deal with their personal demons. He might sit down with Jason and talk about his past traumas and how to move forward. With Tim, it could be about his insecurities in the Bat - family. And for Damian, Nightwing could guide him on how to better fit into the family and society outside of just being a warrior.
Nightwing would likely be more empathetic with Jason. Given Jason's troubled past, Nightwing would be patient and understanding. He'd probably let Jason vent his frustrations and anger in a safe way. With Tim, Nightwing might be more of a mentor in terms of detective work. He'd share his knowledge and experiences to help Tim grow in that area. For Damian, Nightwing would be firm yet gentle. He'd enforce rules but also make sure Damian feels like part of the family and not just an heir to be molded.
They could be original characters created specifically for this fanfiction. Maybe they are two young lovers in a fictional town, with their own dreams and personalities. Damian could be a kind - hearted but sometimes reckless guy, while Mar might be a more cautious and intelligent girl.
One possible fanfic could involve a battle against a powerful villain. Nightwing might get injured while trying to protect Gotham. Batman then has to step in not only to defeat the villain but also to take care of Nightwing. He could use his advanced medical knowledge and resources in the Batcave to nurse Nightwing back to health.
He might try to reason with kaldur. If Nightwing can make kaldur see that what he's doing is wrong or that there are better ways to achieve his goals, kaldur could let him go. Nightwing is known for his charisma and intelligence in such situations.