In some fanfictions, Hermione will initially be shocked and a bit scared. But then she'll pull herself together and try to negotiate with Snape. She might offer him something else in return for him dropping the blackmail, like helping him with his research in a different way than he originally demanded.
Hermione may also start to scheme. She'll use her intelligence to come up with a plan. For instance, she might start to collect evidence against Snape, something that she could use to counter his blackmail. She'll research old school rules or find out secrets about Snape that she can hold over his head instead.
She might initially be shocked and scared. But then she would start to think rationally and try to find a way to outwit Snape. For example, she could start to gather evidence against Snape's own wrongdoings, if there are any, so that she can turn the tables on him.
She often tries to ignore it at first. She's focused on her studies and doesn't want to give the bullies the satisfaction of a reaction.
Snape might initially be shocked. He's not one to show much emotion openly, but internally he could be very disturbed. He might start investigating what happened to Hermione immediately, using his skills in potions and magic to try and find a cure or at least understand the cause.
Hermione might initially be very suspicious. Given her intelligence and wariness, she would not easily fall for the temptation. She would likely question Snape's motives and try to analyze the situation from all angles.
Hermione would likely react with her characteristic intelligence and courage. She would probably try to use her vast knowledge of magic to find a way to escape or at least resist Fenrir. For example, she might try to use spells that could incapacitate him temporarily. She would also be likely to try and outwit him in conversation, looking for any weaknesses or loopholes in his plans.
Snape might initially be taken aback. He's used to students being intimidated by him, so Hermione's outburst could shock him into momentary silence. Then he might retaliate with his usual sarcasm, trying to put her in her place.
Often it starts with Hermione showing an unexpected interest in Snape's area of expertise. For instance, she might ask him for extra help in potions with a bit of a twinkle in her eye and a flirty tone in her voice.
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.
Hermione often shows great courage in these situations. At first, she might be scared, but she soon overcomes it. She tries to gather information about her kidnappers and their plans. If they are trying to 'adopt' her, she questions their motives and tries to find out what they really want from her. She may use her intelligence to manipulate the situation to her advantage. For instance, she could pretend to go along with their adoption idea while secretly planning her escape. She also tries to stay true to her values. If her kidnappers have a different view on things like the treatment of Muggles, she will not be afraid to speak up and defend her beliefs, even in a captive situation.