Well, one reason could be that MHA is interested in different superhero universes and wants to explore how Batman's world is depicted in fan - made stories. Another reason might be for inspiration in terms of storytelling or character development, as Batman has a rich and complex character history.
Maybe to save the Justice League from a powerful enemy. He might sacrifice himself if it means the others can escape or defeat the foe.
It might be related to financial aspects. If the sales of the graphic novel have been consistently low, the publishers may decide to end it. Another possibility is that the creative team has had internal disagreements and they can't continue working together on the project. This could lead to the decision to end the Batman graphic novel. Also, sometimes a series is meant to be a limited run from the start, and 'to end on' could just be the natural conclusion of that planned run.
One reason could be the inaccurate characterizations. Fanfiction writers might not fully understand the nuances of Nightwing or Batman's personalities, and Nightwing hates seeing a wrong version of them. For instance, if Batman is made too soft or too harsh in a way that doesn't match the established canon.
He could be curious about how other fans perceive the events in Naruto Shippuden. Fanfictions can offer unique interpretations and perspectives that might give him new insights.
One possible reason could be mind control. Maybe some villain has taken over Superman's mind and made him do it. Another reason might be a fundamental difference in their ideologies that has escalated to the point of no return.
One reason could be a misunderstanding. Maybe Batman suspects Wonder Woman of being involved in something she's not, like a potential threat to Gotham that he misinterprets. Another could be ideological differences. Batman is very much about justice in his own city, while Wonder Woman has a more global and myth - inspired view of justice.
One reason could be that Bruce Wayne never had the traumatic event that led him to become Batman in the original story. Maybe his parents' death was prevented somehow, so he never felt the need for vengeance and justice in that extreme way.
One reason could be to explore a darker side of their relationship. Maybe the writer wants to show that even heroes can have moments of extreme frustration or anger towards their sidekicks. It could also be a way to shock the readers and make them think about the characters in a new and unexpected way.
He could have a quirk like 'Enhanced Intellect', which would further boost his already incredible detective skills. This would make him able to analyze situations even faster and come up with strategies on the fly.
Some writers might be interested in exploring the darker side of human nature. They could use the well - known Batman - Robin relationship and twist it to show how power dynamics can go wrong. It's also possible that they want to create shock value to get more attention for their work.