Alfred would be extremely worried. He has always been like a father figure to Bruce and would fear for his safety. He might try to convince Bruce to go into hiding or find a way to reverse the unmasking. Dick Grayson, on the other hand, would be shocked at first but then would likely step up to support Bruce. He'd understand the reasons behind it to some extent, having been Robin and knowing the pressures of the superhero life.
The public's reaction would be a mix. Some would see Bruce Wayne as a hero for his work as Batman. They might admire his courage for unmasking himself. However, others would be angry. They might feel betrayed that Bruce had been hiding this identity for so long. And there would be those who would be afraid. They'd worry that now that Bruce Wayne is unmasked, Gotham would be more vulnerable to attacks from villains. His business partners would also be in a turmoil. Some might distance themselves from him, while others might try to use this situation to gain more control over Wayne Enterprises.
Well, it might be that Bruce Wayne unmasked himself as part of a grand plan to draw out a particular enemy. He could be thinking that by making himself vulnerable, the enemy would come out of hiding, believing they had the upper hand. This would be a very risky move, but Bruce is known for taking risks. And then there could be a lot of drama as the public and the other characters in the story react to this revelation.
Iron Man might be protective. He'd probably see Spiderman as a young protege and would want to keep his identity safe using all his tech resources.
He might develop a greater sense of humility. Without the Batman persona to fall back on, he has to face his own limitations as a person. For example, he may struggle to get people to listen to his ideas for change when he doesn't have the intimidation factor of Batman.
At first, it could be a bit rocky. Bruce is used to his own way of doing things and Buffy has her own independent streak. But they would gradually learn to respect each other. Bruce might be impressed by Buffy's combat skills and her ability to handle the supernatural. Buffy, on the other hand, could learn a lot from Bruce's strategic thinking.
The other characters' reactions could vary widely. His close friends in the fanfic might be in a state of panic, crying and not knowing what to do. Enemies, on the other hand, might see it as an opportunity to take advantage, or they could also be secretly worried depending on the complexity of their relationships. And there could be those characters who are just bystanders, shocked at first and then trying to figure out what happened.
Obviously, Bruce Wayne's son is a central character. Alfred Pennyworth often makes an appearance as he is an important figure in the Wayne family. Dick Grayson might also be popular as he can act as a mentor or a brother - like figure to Bruce Wayne's son. And of course, the villains from the Batman universe like the Joker or Ra's al Ghul can also be included to create conflict.
The dynamic could be complex. Thomas might be both proud and worried seeing Bruce as Batman. Proud that his son is carrying on the legacy, but worried about the dangers. He could be overprotective at first.
The encounter could be filled with tension. Bruce might be angry at first, blaming Thomas for leaving him so early in life. But as they talk, they start to understand each other better. Thomas could share his own hopes and dreams for Gotham that he never got to fulfill, and Bruce could see a new side of his father. The description could include details of their body language, like Bruce clenching his fists at first and then gradually relaxing as they talk.
Well, in a fanfic with Bruce Wayne as president, he'd probably bring a whole new level of efficiency. He's used to running Wayne Enterprises, so he'd know how to manage a large organization like the government. He might form some sort of 'Bat - team' of experts to help him in different areas, like economic advisors, scientists, and security experts. Also, his no - nonsense attitude would mean he'd cut through a lot of the bureaucratic red tape.
One great fanfic is 'The Father - Son Bond'. It beautifully explores the complex relationship between Bruce and Damian. It shows how Bruce tries to be a good father while also dealing with his role as Batman, and Damian's struggle to fit into this new world with his own strong - willed nature.