Well, Draco could be very conflicted. On one hand, he has his own pride and his Slytherin upbringing which might tell him to stay away. But if he has developed deeper feelings for Hermione in the fanfic, he might put aside their past differences. He could start by using his family's resources to find a cure or at least better treatments for her cancer. He may also become more protective of her, keeping her away from those who might be unkind about her illness.
Hermione could become withdrawn. She might isolate herself from her friends for a while, spending her time in the library trying to make sense of it all. She might also feel a sense of betrayal, especially if they had some sort of understanding or relationship developing.
Draco might be initially shocked. He's used to seeing Hermione as a strong adversary, so seeing her cry would be unexpected. He could just stand there, not knowing how to react at first.
She might be initially shocked. After all, Draco is usually seen as this tough Slytherin. But then she could feel sympathy. For instance, she might offer him a handkerchief without saying much at first.
She might be heartbroken at first. Hermione is someone who invests deeply in her relationships. She would likely retreat into her studies as a way to cope, burying herself in books to try and forget the pain.
In these stories, their relationship often develops through shared adversity. Since they are dealing with cancer - related issues, they have to rely on each other. For example, Draco might provide the financial or family - related resources while Hermione uses her intelligence to analyze the situation. This mutual dependence starts to break down the walls between them.
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.
Hermione might initially be furious. She is a strong - willed character, so being tied up against her will would surely make her angry. She would probably start using her wits right away, trying to figure out a way to free herself, whether it's through magic or by tricking Draco.
Hermione could also be more understanding in some fanfictions. If she senses that there's something deeper behind Draco's actions, she might try to calm the situation down. She could ask him why he did it instead of immediately retaliating. Maybe she sees a glimmer of vulnerability in his eyes and decides to approach the situation in a more empathetic way. This could then lead to a conversation that changes their relationship for the better.
Hermione might be initially very hurt and angry. She's a proud and strong character. She could cut Draco off completely and refuse to have any communication with him. When Draco shows regret, she may be skeptical at first. After all, he has broken her trust. But deep down, she might still have some feelings for him, so she could be in a state of internal conflict.
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.