No, it is completely inappropriate. Classroom is a place for learning and such sexual content in a fanfiction related to a character like Izuku is not acceptable in a general moral and ethical context. It goes against the positive and educational values that the original work might represent.
One negative impact is that it can corrupt the positive image of the character Izuku. He is usually seen as a symbol of hope and growth, and this kind of inappropriate content can distort that. Another impact is that it can be disturbing to many fans, especially those who look up to the character for positive inspiration. It can also make the overall fan community seem less family - friendly and more seedy.
On the other hand, it could also lead to better understanding. If Izuku snaps and then later explains his reasons, it might bring the class closer together. They could realize that he has been dealing with a lot and become more empathetic towards him. However, in the short term, it will likely disrupt the usual harmony in the class. Some students might be shocked and not know how to react, while others might take it personally and become defensive.
One reason could be stress. Izuku might be under a lot of pressure to keep up with his training and the expectations of being a hero. Class 1A's constant high - energy and sometimes chaotic behavior could push him over the edge. Another reason could be misunderstandings. If they misinterpret his actions or motives, he might snap in frustration. For example, if they think he's showing off when he's actually just trying to help.
You can try searching on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms usually have a wide variety of fanfictions, and you might be able to find ones related to Class 1A watching Izuku there.
One interesting story could be where Class 1A watches Izuku's training sessions secretly and are in awe of his determination and growth. They might then start to understand him better and change their perception of him.
Definitely not. 'My Hero Academia' is a popular franchise that has a wide audience including younger fans. Creating such sexual fanfiction violates the spirit of the original work which is about heroism, friendship and growth. It also creates an uncomfortable and unethical environment within the fan community.
The quirk could be turned into a 'vitality quirk'. Izuku's quirk might be that he can sense and transfer a type of life - force energy. This energy is related to the concept of sexual energy in a very abstract way in that it represents the life and passion within a person. But in the context of the story for a younger audience, it's just about him being able to boost the energy of his friends when they're tired or weak, or using it to heal minor injuries.
One possible plot could be that Izuku's sex quirk is more about an ability to sense strong emotional bonds similar to romantic or sexual attraction. He could use this to help his friends in relationships, like sensing when there are unspoken issues between couples. For example, he might be able to tell if one friend is attracted to another but is too shy to admit it, and then he can nudge them in the right direction in a very innocent way.