She might initially be defensive. Hermione is proud of her intelligence and actions, so she could start by trying to justify what she did. For example, she could say that she was only trying to help or that she had good intentions.
One possible reason could be that Hermione's behavior might have put herself or others in danger. For example, if she was being overly reckless in her pursuit of knowledge, like delving into dark magic without proper precautions. Sirius, having experienced a lot in the wizarding world, would be worried about her safety.
Sirius would probably be very concerned. He might immediately ask her what's wrong and offer her a handkerchief to dry her tears. He has a bit of a wild side, but he also has a big heart, especially when it comes to those he cares about or sees as in need of help.
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 Then she could become very sad and withdrawn.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.
Hermione could also try to reason with Draco. She'll probably start a conversation, trying to understand his motives for capturing her. She might appeal to his better nature if she believes he has one, or try to make him see the error of his ways by using her logical arguments.
She could be conflicted. On one hand, she might be attracted to both in different ways. Sirius's charm and rebellious nature could draw her, while Remus's intelligence and quiet strength might also appeal to her. So she might struggle with her feelings, trying to figure out which, if either, she truly has deeper feelings for.
Perhaps Hermione is so overjoyed that she immediately hugs Ron. She might have been secretly hoping for Ron to ask her all along. She then starts talking about what they should wear and how they can make their entrance at the Yule Ball really special.
She might be initially confused. Hermione is a very intelligent girl, but when it comes to emotions, especially unexpected coldness from a close friend like Harry, she may be at a loss. She could try to talk to Harry to find out what's wrong. If he refuses to communicate, she may become frustrated. For example, she might start to study even more intently as a way to distract herself from the situation.
She would probably be very hurt and angry. Hermione is a strong - willed character, so she might immediately start trying to find out the truth and clear her name.