At first, Hermione might be in shock. But then she would likely use the incident as fuel for her activism. If the fanfiction is set in a context where there are issues of discrimination (like blood purity), she could use what Draco did to her as an example of the Slytherin's cruel behavior towards Muggle - borns. She would stand up in the Great Hall or in class and give a passionate speech about acceptance and respect.
Hermione could also be very hurt. Her hair is part of her identity, and having Draco, who she already has a strained relationship with, do something so cruel would cut deep. She might go to her friends, Harry and Ron, for support. They would likely be just as angry as she is and plot some sort of revenge against Draco and his Slytherin friends.
Perhaps it's part of a power play. Draco comes from a pure - blood family and Hermione is a Muggle - born. In some fanfictions, this power dynamic is explored more deeply. By cutting her hair, he is trying to assert his superiority over her. It could also be an impulsive act in the heat of an argument. They might be arguing about something like blood purity or house points, and he lashes out in a very physical and mean - spirited way.
Hermione might initially be shocked and afraid, but she would quickly gather her wits. She would assess Draco, trying to figure out if there was any way to sway him to her side. Given her ability to see the good in people, she might try to appeal to any sense of morality Draco has left, all while secretly planning her escape or a way to undermine Voldemort's plan of using her as a pawn against the good side.
Hermione might be shocked at first. She has always seen Draco as an adversary, so a neck kiss from him would be completely unexpected. She could push him away immediately and demand an explanation.
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.
Another reaction could be confusion. Draco might not know how to feel. On one hand, he has his Slytherin pride and his clothes are part of that. But on the other hand, seeing Hermione in his clothes gives him a strange feeling in his stomach. He might end up being more curious about Hermione and her reasons for wearing his clothes.
Hermione's friends from Gryffindor would be a mix of disbelief and concern. Neville, for example, would be worried that Draco might be using Hermione in some way. Luna would be more accepting, seeing it as a unique and interesting relationship that defies the norms of the wizarding world. As for Draco's friends from Slytherin, they would also be shocked. Some might see it as a betrayal of Slytherin values, while others might be intrigued by the power dynamics at play between a Muggle - born witch and a pure - blood wizard.
Draco might immediately become defensive. He would probably try to shield Hermione from his father's wrath at first. He could also be filled with fear, knowing how strict and unforgiving his father can be.
Hermione's parents might be initially shocked. They know Draco's family's history and reputation. But if they see how much Hermione loves him and how Draco has changed, they could come around. They would likely be more concerned about Hermione's happiness in the long run.
Harry and Ron would probably be shocked at first. Ron, especially, might have a hard time accepting it because of his past relationship with Hermione. But eventually, they would come around because they care about Hermione. Ginny would likely be more open - minded and try to be supportive. Other friends from Hogwarts might also be divided, some might be against it because of the long - standing rivalry between the Gryffindors and Slytherins, while others would see it as a chance for unity in the wizarding world.
He could also be protective. Despite their differences, Draco might have some hidden feelings for Hermione. So, when he sees her scared, he might put aside their past enmity and try to comfort her or keep her safe from whatever is causing her fear. For instance, if there is a threat from another student or a magical creature, Draco could use his Slytherin cunning to protect her.