One possible analysis could be that their relationship in fanfic often showcases a strong bond of friendship. Bakugo's explosive personality and Kirishima's more stable and friendly nature create an interesting dynamic. Fanfic writers may explore how they support each other during battles or in their daily lives at school. For example, Kirishima might be the one to calm Bakugo down when he gets too riled up, and Bakugo could inspire Kirishima to be more confident in his abilities.
Kirishima is still alive in the manga. The story doesn't have that plot point. Usually, character deaths are significant events and are clearly shown if they occur.
His quirk could be something like super - speed regeneration. In the original Naruto series, he has a great deal of stamina and the ability to heal relatively fast. But with this quirk, he could recover from even the most severe injuries in seconds. This would mean he could keep fighting no matter how badly he was hurt, and his enemies would find it extremely difficult to defeat him.
Another characteristic is the exploration of his relationships. His friendship with Bakugo is a popular theme. Fanfics might show how they support and challenge each other. Also, his relationships with his other classmates are often explored, like how he can be a source of motivation for them.
Kirishima is from a manga/anime. His back story involves him having a sense of self - doubt initially. He admired those with strong and manly qualities. He worked hard to overcome his insecurities and develop his own strength and courage, eventually becoming a reliable hero - in - training.
One way is through self - sacrifice. If the character uses their evil quirk to save a lot of people at great personal cost, it could be a step towards redemption. For example, if their quirk is something like mind - control and they use it to stop a powerful villain who is about to destroy a city, but in the process they lose their own ability to use the quirk. Another way is by showing remorse and actively trying to make up for their past actions. They could start doing volunteer work in the community, using whatever skills they have (even if related to their quirk in a non - evil way) to help others.
First, consider their motivation for using the Copy Quirk. Are they using it to become the best hero? Or maybe to prove themselves to someone? For example, if they want to be like their idol hero, they might copy only the quirks of that hero at first. Then, think about the limitations of the quirk. Maybe they can only copy a quirk for a short time, so they have to strategize when to use it. This would force them to study different quirks and opponents carefully.