Obviously, Batman/Bruce Wayne himself is a central character. His life would be turned upside down by the revelation of his identity.
Obviously, Batman/Bruce Wayne himself. His butler Alfred would also be heavily involved as he has always been there to support Bruce. Alfred would likely be trying to protect Bruce and keep his remaining secrets safe.
Henry is the main one for sure. Ray, his mentor, would also be a big part of it. Ray might have to deal with the fallout of Henry's identity being out in the open, like handling the media and the public's reaction. Also, Henry's family could be involved. His parents might be worried about his safety now that his identity is known. And then there are the other minor characters from the show who could either support Henry or turn against him depending on the plot.
Obviously, Batman/Bruce Wayne himself is at the center. Alfred Pennyworth would be very involved as he has known Batman's identity all along and would likely be trying to protect it or deal with the consequences if it's revealed. Commissioner Gordon might also play a big role. He has a close relationship with Batman and would be affected by the revelation. Then there are the villains. The Joker could be one of the main villains in such a story, using the revelation to his advantage in some devious way.
Batman himself is obviously one of the main characters. Since it's about his identity being revealed, he would be at the center of the story dealing with all the consequences.
Batman's allies such as Commissioner Gordon could be involved. Sometimes Batman might be angry at Gordon if he feels that the police force is not doing enough to support his fight against crime. Also, other members of the Bat - family like Batgirl could be part of the story. Their actions or decisions might trigger Batman's anger. For instance, if Batgirl decides to take on a powerful villain alone against Batman's advice.
In the 'naruto heritage revealed fanfic', Naruto will surely be a central figure as the story seems to revolve around his heritage. Besides him, characters like Kakashi might be involved as he has knowledge about Naruto's father. Also, characters from the Uzumaki clan could play important roles as Naruto is from that clan. And of course, Jiraiya, Naruto's mentor, who knew a lot about Naruto's family history and the ninja world in general, might be included to help uncover more about Naruto's heritage.
In addition to Danny and his immediate circle, there could be other characters from the Danny Phantom universe. For example, Valerie Gray. If she discovers Danny's identity, she might have a complex reaction. On one hand, she's been hunting ghosts, but on the other, Danny has also been protecting the town. So, her role in the fanfiction could be very interesting, especially in terms of how she interacts with Danny after the identity reveal.
Obviously, Ladybug and Chat Noir are often central. Marinette, who is Ladybug, and Adrien, who is Chat Noir. Also, Hawk Moth as the main villain often plays a role in these fanfictions when the identity is about to be revealed or has been revealed, as his actions can be related to this big event.
The villains could also be important characters in this fanfic. For instance, Orochimaru or Madara might be interested in Naruto's true self, either to use it for their own evil purposes or to try and stop him from fully realizing it. Their presence would add conflict and danger to the story.
Obviously, Naruto is the central character. But other characters like Sasuke could also be involved. Sasuke might be torn between his loyalty to Konoha and his friendship with Naruto. He could either try to bring Naruto back or join him in his exile.