Sasuke's character arc in a My Hero Academia fanfiction could be centered around redemption. Maybe he has some dark past actions in the Naruto world that he's trying to atone for in the MHA world. He could start off using his powers for his own ends, but then realize the importance of heroism and self - sacrifice. He might also struggle with his identity as a ninja in a world full of quirks, and this internal conflict could be part of his character growth.
In a fanfiction, Sasuke's character arc could be about finding a new purpose. He's used to his life as a ninja in the Naruto universe, but in MHA, things are different. He could initially be focused on getting back to his own world, but as he spends time in the MHA world, he starts to care about the people there. He might develop new relationships, learn about the concept of heroism in a different way, and in the end, become a hero in his own right, using his unique skills and experiences to protect the MHA world.
He could start as a naive but powerful character, similar to his early days in Dragon Ball. Then, as he experiences the more complex hero society in MHA, he could learn about teamwork and strategy. Maybe he'd start out thinking he can handle everything alone but then realize the value of his classmates or fellow heroes.
In a fanfiction, Wolverine could have a complex relationship with the villains. Some villains might be afraid of him because of his reputation and power. But there could be a villain who tries to manipulate Wolverine's past traumas. This could lead to some intense emotional and physical battles, as Wolverine has to fight not only the villain's powers but also his own inner demons.
He could be a mentor to some of the more physically - oriented heroes like Kirishima. Logan's no - nonsense attitude and combat experience would be valuable to Kirishima. Or he could have a rivalry with heroes who don't like his more violent approach, like All Might who is all about justice and protecting with a more 'pure' image.
He could start off as a loner, not really understanding the quirk - based society. But as he interacts with the students at UA, he could learn the value of teamwork. For instance, in group battles, he'd realize that combining his alchemy with others' quirks can create more powerful effects.
Another arc could be Shirou coming to terms with the different values in the MHA world. His own set of values from his original story might clash with the hero society's values at first. He might question things like the hero rankings system. As he navigates through these differences, he could grow as a character and find a new sense of purpose within the MHA hero society.
A character who is an outcast or a loner might have the Sharingan. They could use its powers to gain an edge in a world where they are not fully accepted because of their different nature. For instance, they could quickly analyze the quirks of those who bully them and find ways to counteract.
A quirk like energy absorption might be cool for Lucy. She could absorb different types of energy, such as heat, electricity, or even the kinetic energy of an attack, and then release it back in a more powerful form. This would give her an edge in combat and make her a formidable character.
He could have a 'Ninja Arts' quirk. This quirk would allow him to perform all the ninja techniques he knows from Naruto, like the Rasengan or Chidori. His Sharingan could be an additional aspect of this quirk, enhancing his ability to learn and adapt to other quirks he encounters.
He could be a transfer student. Just like how many characters join UA High, Killua could transfer in with his unique set of skills. He would be the cool and mysterious new guy that everyone is curious about.
He could be a mentor. Given his vast combat experience and his ability to master different techniques, he could guide the young heroes in My Hero Academia. Just like how he was trained by Master Roshi and others, he could pass on his knowledge to the likes of Izuku or Bakugo.