She might be initially scared but quickly regain her composure. Uraraka is a brave character. She would likely start looking for ways to escape, using her zero - gravity quirk to her advantage, like floating up to vents or disabling the villains' weapons if she can.
It could be that the villains are part of a secret organization that is interested in experimenting on those with unique quirks like Uraraka's. They capture her and take her to a hidden facility. There, she meets other captives with quirks and together they try to stage a revolt while waiting for the heroes to come to their rescue.
She might confront Harry directly. In the heat of the moment, she could burst out with her suspicions and demand an explanation. For example, she might say, 'Harry, I've noticed you've been acting strange around that girl. Are you cheating on me?'
Shigaraki would likely be disgusted if the fanfic made him seem weak or less of a threat. He'd probably scratch at his neck in irritation. Dabi would be dismissive. He'd think fanfics are just a waste of time and not worthy of his attention. Toga, though, might be intrigued. If the fanfic had a lot of blood and gore in it, or if it focused on her relationships in an interesting way, she could be really into it.
Ichigo would likely be defiant. He's a fighter and would not easily submit to Aizen. He'd probably be constantly looking for a way to escape and would be sizing up Aizen's every move, trying to find a weakness.
Harry would be extremely shocked. He has always seen Snape as a complex figure, and Hermione capturing him would make him question a lot of things. He would likely try to get to the bottom of it and mediate between Hermione and Snape if possible.
Midoriya's family would be ecstatic. His mother would be busy helping with the wedding preparations, giving advice on everything from the dress to the food. Uraraka's family would be equally happy. They would see Midoriya as a kind - hearted and strong young man. Her mother would likely bond with Midoriya's mother over the wedding plans, and the two families would come together to celebrate the union of the two young heroes.
Well, it could be that she was lured into a false sense of security and then ambushed. Or perhaps she made a mistake that gave her captors the opportunity to seize her.
Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
Mentally, Ochaco would struggle. She has the mind of an older person but is trapped in a child's body. She would have to deal with the frustration of not being able to communicate as effectively as she used to. And she might feel a sense of loss for her normal life and the progress she had made in her hero training and relationships.
Will might initially be in shock. He trusts Hannibal to a certain extent, so the betrayal of being kidnapped would be a huge blow. He could be angry and try to fight back against Hannibal.