Midoriya would initially be in shock. But then, his heroic instincts would kick in. He might try to analyze Toga's behavior and find a way to use it against her. For instance, if he notices that she gets distracted easily, he could create a diversion. He would also be thinking about the safety of others. He might worry that Toga has some bigger plan that involves harming his classmates or the city. So he would be constantly looking for a way to not only escape but also stop Toga's potential evil plans. And throughout all this, he would be drawing on his training at U.A. to keep his composure and think rationally.
The other characters' reactions would be diverse. Bakugo might initially be very confused and maybe even mock Midoriya a bit, but deep down he'd still see her as a rival. Uraraka would probably be very empathetic and quickly become a good friend to Midoriya in her new form, helping her with things like getting used to the new body. And All Might would be very supportive, seeing it as just another obstacle Midoriya has to overcome in her journey to become a great hero.
Other characters' reactions can vary widely. Some of the more empathetic classmates, like Tsuyu, might offer words of comfort and stay by his side. Mineta might be a bit more cowardly, but still show some concern. The teachers, such as Aizawa, would take charge of the situation. Aizawa would ensure Midoriya gets proper medical attention and also start an investigation if the injury was due to foul play. His mother, if she were to find out, would be extremely worried and rush to be by his side as soon as possible.
Well, there are also those characters who might be a bit shocked or confused. Take Levi from Attack on Titan. He's a very serious and no - nonsense type of character. If he were to read some of the fanfic about him that deviated too much from his own self - perception, like being made into a comical or overly emotional character in the fanfic, he might be taken aback at first. But then he might also realize it's just a different interpretation and not take it too seriously.
Well, it depends on the nature of the fanfiction. Some anime characters might be amused if the fanfiction is light - hearted and full of comical situations. For example, if it's a fanfic about a cooking competition among the characters from a shonen anime, they might react with good - natured laughter and competitiveness. They could also be confused if the fanfiction takes their story in a very strange or unexpected direction, like suddenly making a character from a historical anime end up in a space adventure.
Midoriya's family would be ecstatic. His mother would be busy helping with the wedding preparations, giving advice on everything from the dress to the food. Uraraka's family would be equally happy. They would see Midoriya as a kind - hearted and strong young man. Her mother would likely bond with Midoriya's mother over the wedding plans, and the two families would come together to celebrate the union of the two young heroes.
Kakashi would be very observant. He would look for how the fanfiction writers understand the world of Naruto, the values and the moral lessons. He might even use some of the creative ideas from the fanfiction in his own teachings if he thought they were valuable and in line with the spirit of the original story.
There could be characters who are outraged. If the fanfiction distorts their personality or makes them do things completely against their nature, they may be very angry. For example, a noble character made to act like a coward in the fanfiction would likely not take it well.
They might be confused at first. RWBY has its own unique lore and concepts that are different from many anime. So anime characters may need time to understand things like Grimm and Huntsmen. For example, if Goku from Dragon Ball was watching, he'd probably be like 'What are these strange monsters?'.
They could be surprised. The fanfiction might show them in scenarios they never imagined, like a shy character being in a very bold and adventurous situation.