Well, in a lot of these fanfictions, Stiles can get beat up due to his own recklessness. He might be so determined to solve a mystery or help his friends that he doesn't think about the consequences and ends up in a dangerous situation where he is outnumbered and beaten up. Also, there could be miscommunication. Maybe someone thinks he has done something wrong when he actually hasn't, and they take matters into their own hands and beat him up.
It could be an antagonist character in the Septiplier fanfiction world. Maybe someone who has a grudge against Jack for some reason, like a rival in a game or a love interest situation gone sour.
One possible reason could be that he's gotten on the wrong side of a powerful client. Maybe he uncovered some shady business deals of the client during a case, and the client decided to take revenge by having him beaten up. Another reason might be related to his past. If some of his old associates from his pre - Harvey days found out he was now working in a high - profile law firm, they could be jealous and target him.
He might be in shock at first. Mike could just sit there, trying to process what has happened. Then, he would probably be angry. He's not the type to just let things go, so he'd start thinking about who could be behind it and how to get revenge.
Lucy getting beat up can also be a turning point for her character development. It might make her realize she needs to train harder or develop new magic skills. This could lead to her going on a training journey, which would be an interesting sub - plot in the fanfiction.
One possible reason could be that she's in the wrong place at the wrong time. Maybe she stumbles upon a group of antagonists who target her because she's known for her association with certain powerful characters. For example, if there are enemies of her friends or family, they might use her as a way to send a message.
In some fanfiction scenarios, Sakura could be under the influence of a dark power or a curse. This power might be corrupting her mind and making her lash out at Naruto for no real reason. It could also be a case where Sakura is trying to prove herself as a strong kunoichi and Naruto is just in the wrong place at the wrong time, so she uses him as a target to show off her skills.
Sasuke could be one. Given their complex relationship, there could be a situation where Sasuke's newfound power or different ideology leads him to fight and beat Naruto in a fan - made story.