It could be Draco Malfoy. In some fanfictions, Draco might be pushed to such an extreme by his family's beliefs that he resorts to physical violence against Hermione. He might punch her out of jealousy or to assert his so - called superiority.
Maybe it's a story where Hermione accidentally gets caught in the middle of a wizard duel gone wrong. One of the angry duelists punches her in a fit of rage. Then the story could focus on how she deals with the injury and the chaos that follows, as well as her pursuit of justice for the unprovoked attack.
He could become more isolated. After being punched, his friends might avoid him for a while. For example, if Harry punches him, Harry might need some time to cool off and not want to be around Ron. This would make Ron feel really lonely and regret his actions that led to the betrayal.
Well, in a 'Gohan gets punched' fanfiction, it might start with Gohan in a tournament. He's facing a really tough competitor. This competitor, using a sneaky move, punches Gohan right in the gut. Gohan feels the pain but uses it as motivation. He then analyzes his opponent's fighting style more carefully. He dodges the next few attacks and counter - punches with his own signature moves. It could be a story about Gohan's resilience and his ability to learn from being punched.
One possible scenario could be that it's a case of mistaken identity. Maybe someone thought Annabeth had done something wrong when she hadn't. Another could be in the heat of an argument where emotions got out of control and someone lashed out at her. Or perhaps it's part of a more complex plot where an enemy is trying to send a message to her friends by punching her.
Maybe an antagonist who wants to disrupt the group dynamic. If Annabeth is a key part of a group, punching her could cause chaos and confusion among her friends. It could also be someone who has been influenced by dark magic or some sort of mind - control in the fanfiction. This would make them act against their normal nature and punch Annabeth without really having a personal grudge.
It could be a new, unknown enemy. Maybe someone from a far - off planet who has a grudge against the Saiyans. This character could be really powerful and sees Gohan as an easy target at first, so he throws a punch.
Well, it could be Harry who punches Ron. Maybe Ron betrays Harry's trust in some way, like perhaps revealing a secret of Harry's to the wrong people. And Harry, being really angry about it, punches him in a moment of rage.
Well, in a 'peter gets punched by steve fanfiction', it could be that there is some sort of misunderstanding. Steve might think Peter has done something wrong, like endanger the safety of others or break a moral code in their world. Or perhaps it's part of a bigger plot where an outside force is manipulating Steve into attacking Peter.
Well, it could be that Naruto misinterprets something Sakura says to Sasuke and makes a comment that offends her deeply. Sakura, being the strong - willed character she is, doesn't hold back and punches Naruto. This could then start a chain of events where Naruto tries to make amends, and through this process, their friendship becomes stronger as they understand each other better.