Well, Ginny would be very protective. She'd be by Hermione's side, not leaving her alone. The Weasley family as a whole would also be involved. Mrs. Weasley would come with some home - made remedies and fuss over Hermione. Fred and George might even try to create some new products on the fly to help with her injury, using their inventive minds to contribute to her healing.
Harry and Ron would probably be very worried. They'd rush to her side immediately. Harry might use his skills to try and find a way to heal her quickly, while Ron would be freaking out a bit but also trying to be helpful.
Her friends would first be in shock. Then they'd start using their different skills and resources. Luna might offer some unique and perhaps a bit odd - sounding remedies. Neville would bring in some herbs from the Hogwarts greenhouse that he thinks could help in the healing process. All of them would be united in their concern for Hermione and do whatever they can to aid her recovery.
Harry would probably be extremely worried. He'd immediately rush to her side, trying to figure out how to help. Ron, on the other hand, might be in a bit of a panic at first but then would do whatever he could to protect her while waiting for help. Hagrid might bring some of his home - made remedies, thinking they could work on her injury.
Ron would be devastated. He might initially be at a loss for what to do. But then his Gryffindor courage would kick in. He'd start researching every possible cure or treatment for her injuries. He'd be the one to comfort Harry and the others while also being the most vocal in demanding justice for Hermione. His relationship with Hermione, whether you see it as just friends or something more, would make him act in a very passionate and protective way.
It could also be that they are working on a new spell together in Snape's private laboratory. A miscalculation in the magic could lead to an explosion or a backfiring of the spell, causing them both to get injured.
She might be initially shocked. After all, she would have trusted her friends a great deal. Then she could become very sad and withdrawn. She might throw herself into her studies even more as a way to cope, trying to distract herself from the pain of losing her friends.
After the initial reactions, Hermione may choose to isolate herself for a while to figure things out. She would use this time to study and research, trying to find a solution to the problem with her friends. She might also look for new allies or resources within the fanfiction world to help her deal with the situation.
She might be initially shocked and hurt. Hermione is a character who values her friendships deeply, so their sudden departure would be a big blow. She could spend some time in denial, not believing that they would actually leave her.
She might withdraw. Hermione could become quiet and start spending more time alone, like going to the library even more often than usual. This is her way of protecting herself from further hurt.
Hermione could also get angry. She's a strong - willed character. So, instead of just accepting the situation quietly, she might confront her friends and demand to know why they are ignoring her. This could lead to a big argument or a revelation about what's really going on.
She might be initially shocked. But being Hermione, she would quickly gather her wits and start planning. She could use her vast knowledge of magic to find her way or to signal her friends.
She might initially be in shock. Hermione is used to relying on her friends, so the betrayal would be a huge blow. She could then become angry and start to isolate herself. In some fanfictions, she might try to figure out why they did it on her own, using her intelligence to uncover the truth.