One possible reaction is confusion. Peter would have so many questions swirling in his head like why was he adopted, who are his real parents, etc. He might also experience a mix of emotions. On one hand, he might be sad about the lies or lack of information he's been living with, but on the other hand, he could be excited to learn about a new part of himself and his past. He may even see it as an opportunity to expand his understanding of who he is and how he fits into the world, both as Peter Parker and as Spider - Man.
He could be shocked at first. Just the sudden realization that the people he thought were his biological parents all his life are not would be a huge blow.
It would likely make him question his identity a great deal. He might start to wonder about his biological parents and what traits he got from them. This could lead to a whole new self - discovery journey in the fanfiction.
He might be completely devastated. In many fanfictions, Edward enters a state of deep despair. He could isolate himself from others, feeling like his world has ended without Bella.
He might experience a great deal of confusion at first. He has been living a certain life with a wife, and suddenly realizing his sexual orientation is different can shatter his self - perception. He could also feel guilty, especially towards his spouse, as he has entered into a marriage under false pretenses in a sense.
He might be shocked. Draco has always seen Harry as an equal rival in some ways, but finding out he is Lord Black means Harry has a whole new level of status. So, shock is a very likely initial reaction.
In some fanfictions, Naruto is completely devastated. He might go into a state of shock at first, unable to believe the news. Then he could be filled with intense grief and anger, blaming himself for not being there to protect Jiraiya.
In many fanfictions, Naruto is initially in a state of shock. He can't believe that Jiraiya, his mentor, is gone. He might go into a period of deep sadness and isolation, withdrawing from others as he tries to process the loss.
Draco may initially react with disbelief. But as he realizes it's true, he could have a complex range of emotions. He might be disgusted by the act itself. His Slytherin nature might make him want to be cunning in dealing with the situation, perhaps by finding out more about the incident in a secretive way. He could also have a moment of self - reflection, thinking about how his own actions in the past might have added to Harry's stress or made him more vulnerable. And ultimately, he could be motivated to help Harry heal, whether it's through emotional support or taking more practical steps like helping him report the crime if that's applicable in the fanfiction world.
He might be shocked and filled with anger. He could immediately want to comfort Harry and ensure his safety.
Naruto could also be a bit angry at first. Angry that she had been away from him all this time. But then that anger would quickly turn into overwhelming love and relief. He would have so many questions to ask her about why she wasn't there as he was growing up, but at the same time, he would be so glad to have her there now.
In some fanfictions, Naruto could find out in a very emotional way. For example, his daughter might be in danger, and when he discovers she is his, his feelings of love and the need to protect her are intensified. He might also struggle with the fact that he has missed out on part of her life so far. He'd then start to make up for lost time by spending as much time with her as possible, teaching her ninjutsu and sharing his own life experiences.