Well, obviously Batman and Nightwing are the main characters. Batman, the dark and brooding protector of Gotham, with his vast array of gadgets and skills. And Nightwing, the acrobatic and more light - hearted hero who was once Robin.
There could also be other supporting characters. For example, Alfred, Batman's loyal butler. He might play a role in providing information or assistance to Batman and Nightwing during their adventures. Also, Commissioner Gordon could be involved, as he often works with Batman to keep Gotham safe.
Another possible plot is that they discover a long - lost secret about Gotham's past together. This could lead them on a journey through the city's underbelly and old, forgotten places, uncovering clues and facing challenges along the way.
I'm not sure who the absolute best is, but some popular ones might be those who have a deep understanding of the Batman and Nightwing characters. Maybe authors who have been following the comics for a long time.
Obviously, Nightwing himself would be the main character as he's the one taking on the Batman role. Robin, if there's a younger Robin at the time in the fanfiction, would also be a key character. He might look up to Nightwing in his new role or have some doubts about him filling Batman's shoes.
Well, obviously the two main characters are Batman from the normal DC universe and Flashpoint Batman. Batman is the well - known Dark Knight, a symbol of justice in Gotham. Flashpoint Batman is from an alternate timeline, with different experiences and a potentially different personality.
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.
The theme of family also runs strong. The Bat - family is complex, and when Nightwing and Batman meet, it can highlight the family aspect. They might have disagreements like any family members, but ultimately they are there for each other. This is seen in fanfictions where they protect each other from threats both external and internal to the family.
I would recommend 'Nightwing's Ascent'. This fanfic is amazing as it focuses on Nightwing's growth while still maintaining his connection with Batman. It has some really cool action scenes and emotional moments that make it a great read.
One interesting plot could be that they team up to take on a new and powerful villain in Gotham. Maybe this villain has some unique powers that force Batman and Nightwing to combine their skills in unexpected ways.
Ra's al Ghul could also serve as the main antagonist. He might have a new plan for Gotham that involves using Catwoman as a pawn. He could be aware of her relationship with Batman and try to use it to his advantage. Batman would have to not only save Gotham but also rescue Catwoman from Ra's al Ghul's clutches.
Obviously, Batman and the members of the Justice League are the main characters. Batman is the Dark Knight, known for his intelligence and combat skills. And then there's Superman, the Man of Steel with super strength and other powers. There's also Wonder Woman, a powerful Amazon warrior.