In this fanfiction, perhaps there is a misunderstanding between Luke and Percy. Luke might think Percy has betrayed him in some way, like siding with the wrong people in the context of their fictional world, and thus resorts to violence by beating him up.
Perhaps in the fanfiction, Percy is under some sort of dark influence. This could be from a new, unknown magical force. This influence makes him see Jason as a threat to his friends or himself, so he attacks Jason. Jason, on the other hand, is initially confused but then tries to fight back to defend himself while also trying to figure out what's wrong with Percy.
Obviously, Luke and Percy are the main characters. Luke is the one doing the beating, and Percy is the victim in this scenario.
One possible plot could be that they discover their brotherhood early on. They then team up to face the various challenges in their world. Maybe they use their combined powers, like Percy's water - related abilities and Luke's combat skills, to fight against a common enemy, such as a powerful monster that threatens their home.
A great plot could involve a prophecy that centers around their brotherhood. Percy and Luke are initially on opposite sides due to Luke's association with the Titans. But when they find out they are brothers, it throws everything into chaos. They have to navigate their relationship while also trying to figure out how to fulfill or avoid the prophecy. There are a lot of emotional moments as they struggle with loyalty to their respective camps and to each other as family.
Well, one possible plot could be that Luke kidnaps Percy to use him as a bargaining chip. Maybe he wants to trade Percy to the Titans for more power or a higher position. Luke might keep Percy in a secret location, like an old, abandoned temple. Percy, of course, would try to escape and find a way to warn his friends at Camp Half - Blood.
Maybe Sakura gets angry at Naruto for some misunderstanding, like he accidentally ruins one of her important medical experiments. So she decides to beat him up to teach him a lesson.
Well, in such a fanfiction, perhaps Sasuke has some sort of plan that involves Hinata in a negative way. Naruto discovers this and decides to beat up Sasuke to protect Hinata. It could also be part of a bigger struggle where Sasuke's actions are seen as a threat to the future Naruto envisions with Hinata, so Naruto takes matters into his own hands to stop him.
One possible reason could be a misunderstanding. Maybe Sakura makes a decision that Naruto strongly disagrees with regarding the safety of the village or their friends. For example, if Sakura decides to trust an enemy without Naruto's knowledge, Naruto might get so angry that he lashes out at her.
One possible reason could be a simple rivalry that has boiled over. Maybe they were competing for the same mission, and Naruto's determination to prove himself got the better of him. He might have seen Kiba as a threat to his goal of becoming Hokage, thinking that if Kiba succeeds in a high - profile mission, it could overshadow his own achievements.
One possible plot could be that Luke initially starts out as a rival to Percy but as they interact more, he begins to see Percy's true self and falls for him. Maybe they are forced to work together on a dangerous quest and during that time, Luke's feelings develop.