Izuku Midoriya is a likely character. He has a strong sense of justice and is always willing to put others before himself. His determination to be a hero makes him a prime candidate for self - sacrifice. Bakugo Katsuki could also be involved. Despite his tough exterior, he has a good heart and would sacrifice for his friends and to prove himself as a true hero.
One common theme is heroism. Characters might sacrifice themselves to save others, just like real heroes do. It shows their selfless nature. Another theme could be redemption. A character who has made mistakes in the past might sacrifice themselves as a way to make up for those wrongdoings. And friendship is also a big theme. They sacrifice for their friends to protect the bond they share.
Ruby is often a central character in sacrifice - related stories. Given her leadership role and her powerful Silver - eyed Warrior abilities, she might be put in situations where she has to sacrifice something for the greater good. For example, she could sacrifice her own safety to buy time for her team to escape a dangerous situation.
I think the students like Kaminari and Sero would be involved. Kaminari with his goofy personality might initiate some pranks, and Sero could use his tape quirk to set up some elaborate prank setups. Also, the teachers like Aizawa could be involved. He might play a prank on the students to teach them a lesson in a rather unorthodox way. Another character could be Todoroki. His rather stoic nature could be a great contrast to the chaos of a prank.
Obviously, Izuku Midoriya will be the central character. His friends from U.A. High like Ochaco Uraraka and Tenya Iida are likely to be involved. They would be there to support or oppose Izuku depending on the nature of the spiral he's in. Also, All Might might play a role as Izuku's mentor, guiding him through whatever challenges the spiral presents.
Power and responsibility is a big theme. Just like in the original My Hero Academia, the self - insert characters have to learn how to use their powers (if they have new or different ones) responsibly. Also, there's often a theme of acceptance. They need to be accepted by the hero society and the other characters, and they also have to accept the new world they're in. For example, in many stories, the self - insert character may come from a different background and has to adapt to the quirks and the hero - villain dynamic of the My Hero Academia world.
Well, for a 'My Hero Academia villain self - insert fanfiction', you need to focus on character design. Decide on your villain's quirk. It should be something that reflects your character's nature and goals. Next, plan the relationships. Who are your allies? Who are your enemies among the heroes? You can also draw inspiration from existing villains in the series. And don't forget about the plot. It could be a revenge story, a power - grab story, or something more complex. Write in a way that shows your villain's perspective and makes the reader understand their actions.
In some fanfictions, Danny's family members can be involved as well. His sister Jazz might be there to support him emotionally or to try and stop him from making a dangerous sacrifice. His parents, who are ghost hunters, could also be part of the story. Their relationship with Danny and their views on his actions can add depth to the fanfiction.
In a darker take, even some of the younger students at U.A. High could die. This would be a very emotional and impactful event. It would show the harsh reality of the hero world and how not everyone is guaranteed to survive, no matter how much potential they have.
First, understand the world of My Hero Academia. Know the quirks, the society, and the existing characters. For a self - insert, give your character a unique quirk that doesn't overpower the story but still makes them stand out. For example, a quirk that can manipulate sound in creative ways. Then, think about their backstory. Maybe they come from a small town and have big dreams. When writing interactions with canon characters, stay true to their personalities. For instance, Bakugo would be brash and competitive, so your self - insert should react accordingly to build a believable relationship.
One common mistake is making the self - insert too overpowered. It ruins the balance of the story. Another is not respecting the established lore of My Hero Academia. For example, ignoring how quirks are supposed to work. Also, creating a character that has no real purpose in the story. They should have goals and motivations that tie into the overall plot.