A frequent theme is self - discovery. The male oc in the 'prison school' setting may learn a lot about himself, his strengths and weaknesses. Also, the theme of rebellion against the unfair rules of the prison school is quite common. In many fanfics, the male oc will lead or be part of a movement to change things. This can make for very interesting and exciting storylines as they face off against the school authorities.
Sure. You can try searching on fanfiction.net. There are often many works in the 'prison school' category. Look for ones that are tagged with'male oc' which usually means male original character. Some popular ones might have interesting storylines and well - developed characters.
One idea could be creating an OC who is a brilliant hacker that gets involved with the escape plan. They could use their skills to bypass security systems in the prison. Another could be an OC with a medical background who has to deal with the various injuries during the escape. For example, they could be the one who patches up Michael when he gets hurt.
To develop the characters in a 'Prison School Mari x OC fanfic', start with Mari. Look at her role in the original story. Is she a leader? Then in your fic, show how she takes charge when she and the OC are in a difficult situation. For the OC, create a backstory. If the OC has a troubled past, it can influence how they interact with Mari. Let's say the OC was bullied before, so they are initially hesitant around Mari. But as they get to know each other, the OC starts to trust Mari more. Their relationship then becomes a key factor in both of their character development.
One idea could be that the OC is a new student at the school and Mari is immediately intrigued by their unique personality. They could bond over a shared interest in art, perhaps working together on a project for the school. Another plot could involve the OC getting into some sort of trouble, and Mari helps them out, leading to a deeper connection between them.
One common theme is redemption. For example, a character who has made mistakes in the Naruto world might be sent to the prison school to atone and grow. Another theme is survival. The prison school environment is often harsh, so characters need to find ways to endure.
One way is to reform school discipline policies. Get rid of zero - tolerance policies that are too harsh. Instead, focus on restorative justice practices that aim to repair the harm caused by misbehavior rather than just punish.
One possible plot could be that Naruto, with his determination and unique skills, gets sent to Prison School by mistake. He then uses his ninja abilities to deal with the strict rules and strange characters there. For example, he might use his shadow clone jutsu to attend multiple classes or chores at once, which both confuses and amazes the other students and teachers in Prison School.
To develop a believable OC, start with a clear backstory. For example, if your OC is a criminal in the prison, explain what led them to that life. Maybe they had a difficult childhood or were forced into a life of crime. Also, give them distinct physical and personality traits. A character with a limp and a sarcastic sense of humor would be more memorable.