Uraraka would be heartbroken. She had a special bond with Deku. She would likely be in a state of shock for a while and then use her pain to fuel her determination to carry on Deku's legacy of helping others. She might also be the one to try and keep the class together during this difficult time.
Bakugo would be deeply affected. He might initially deny his feelings, but then would be filled with guilt for all the times he was mean to Deku. He could become more withdrawn and focused on becoming a hero worthy of Deku's sacrifice.
Uraraka would be heartbroken. She was one of Deku's closest friends. She might lose some of her usual cheerfulness and become more focused on finding out who or what was responsible for his death. She could also struggle with her own self - confidence in using her quirk, as Deku was always an inspiration to her.
Deku would be devastated. He has always seen Bakugo as both a rival and someone he deeply cares about. His reaction would likely be a mix of extreme grief and guilt. He might feel that he could have done more to protect Bakugo. Kirishima, who is Bakugo's friend, would be heartbroken. He would probably be filled with anger towards whatever caused Bakugo's death and would be determined to make the culprit pay. Ochaco and the other classmates would also be in shock. They would come together to support each other through the difficult time, but they would also feel a great sense of loss as Bakugo was an important part of their class dynamic.
His friends would be really shocked at first. Uraraka might be the first to try and comfort him, seeing as she has a kind heart. Bakugo, on the other hand, would probably be both confused and a bit angry at the situation. All - Might would likely feel a sense of responsibility to protect Deku even more than before. The teachers at UA would probably start researching how to reverse the transformation immediately.
The characters would have a range of reactions. Some would be in disbelief. They have witnessed Deku's journey from a quirkless boy to a powerful hero - in - training. So, seeing him as a villain in a fanfiction would be like a complete 180 - degree turn. Midoriya's mother would be devastated. She has always supported her son, and to see him as a villain would go against everything she believed in. The teachers at U.A. would be concerned and start to analyze what could have led to this change. Maybe they would question their own teaching methods or if there were any signs they missed during Deku's time at the school.
The heroes in MHA would likely be initially shocked and a bit intimidated by the Doom Slayer. His brutal and direct approach to combat is very different from their more heroic and often rule - bound ways. Bakugo might be one of the first to be both intrigued and challenged by the Slayer's presence, as he respects power. The villains, on the other hand, would probably see the Doom Slayer as a major threat and might try to avoid direct confrontation at first.
The female characters like Ochaco and Tsuyu might feel a sense of relief. Ochaco has often been on the receiving end of Mineta's inappropriate behavior, so she would probably be glad that she no longer has to deal with that. Tsuyu, being the no - nonsense type, would likely think it was a long - overdue consequence.
They may be either amused or annoyed. It depends on how they are portrayed in the fanfiction. If it's a positive and creative portrayal, they might be amused. But if it's a negative or inaccurate one, they could be annoyed.
Some characters might try to understand Deku's motives. Kirishima, who was close to Bakugou, would be angry at first but might also try to find out if there were any extenuating circumstances. However, many would be afraid of Deku, seeing him as a threat now that he has killed one of their own.
Todoroki would be rather indifferent on the surface. He'd read it with his usual calm expression. But if the fanfiction delved into Deku's relationships with his friends, Todoroki might start to think more about his own friendships. If there was a part where Deku helped someone in a really selfless way, Todoroki might respect that and see it as something to strive for in his own actions.
Midoriya's friends like Uraraka and Iida would be extremely worried. They would immediately start looking for him. Uraraka might use her quirk to search in the air, while Iida would lead the ground search with his speed. Bakugo, on the other hand, would be furious. He would probably go on a solo mission to find Deku and take on Todoroki without hesitation.