Leia would be a mix of furious and calculating. She would be furious at being kidnapped by Vader, the symbol of the Empire's tyranny. But she would also be calculating, looking for ways to escape or send a signal to her allies. She might also try to get into Vader's head, using her knowledge of the Force (even if she is not as trained as Luke) to disrupt his thoughts or plans.
Leia would most likely be defiant. She has always been a strong and feisty character. She would probably resist Vader's every move and not be easily intimidated by his presence.
One possible plot development could be that Leia uses her wits to try and outsmart Vader during her captivity. She might attempt to manipulate the situation to her advantage, perhaps by feigning cooperation while secretly planning an escape. Another development could be that Luke and the Rebel Alliance launch a rescue mission. They would face numerous challenges, like penetrating Vader's stronghold and evading his forces. And Vader himself might be conflicted about his actions, given his relationship with Luke and the knowledge that Leia is his daughter, which could lead to some internal struggle within him.
Claire's reaction could be a mix of fear and determination. She would be afraid because she's in a vulnerable position, but she would also be determined to not let Ada succeed in whatever her plan is. She might start by trying to talk sense into Ada, appealing to her better nature if there is one. If that doesn't work, she would look for any weaknesses in Ada's plan or in their current location to make her escape and also try to find a way to stop Ada from doing this to others in the future.
At the start, Ginny would be shocked and terrified when Tom Riddle kidnaps her. However, as time passes, her Gryffindor courage would kick in. She would start to analyze Tom Riddle's motives and actions. She might pretend to be more vulnerable than she actually is to lower his guard. Ginny could also try to communicate with any magical creatures or objects in her vicinity for help. And she would be mentally preparing herself for a fight or escape, using every bit of her magical training and her wits to outsmart Tom Riddle.
Castle would probably be shocked at first. He'd be thinking 'Why is my daughter doing this?'. Then he'd start trying to talk to her, using his charm and wit to figure out what's going on.
Elena would probably be terrified at first. She might try to fight back or escape immediately. After all, Kai has a reputation for being dangerous.
Link would likely be defiant. He's a hero after all. He'd probably try to break free as soon as possible, using his combat skills and wits even while restrained. He might also taunt Ghirahim, trying to make him angry and slip up.
The other members of Team 7 like Sai would be confused. Sai doesn't fully understand emotions like the others, but he would know that this is a bad situation. He would follow Sasuke and Kakashi's lead in trying to find Naruto and Sakura. Tsunade, as the Hokage, would have to make some tough decisions. She would probably send out search parties while also trying to keep the situation under wraps to prevent panic in the village. The other ninja in Konoha would be on high alert. They would be worried that Naruto's actions could be the start of a larger threat, either from within the village or from outside forces.
Annabeth would be furious. She'd immediately start planning a rescue mission. She might call on all of Percy's friends and allies at Camp Half - Blood. Annabeth would use her strategic mind to figure out where Nico has taken Percy and how to get him back.
She might try to manipulate Loki. Natasha is very good at getting into people's heads. She could play on Loki's ego or his own insecurities to gain an advantage. For example, she could pretend to be interested in his plans or offer to help him in some way, all while secretly planning her escape.
Hermione may first try to use magic to defend herself or escape right when the kidnapping is taking place. But if that fails, she will start to analyze the situation. She would think about what she knows of Dolohov from her studies and any previous encounters. Then, she would form a plan. She might even try to find allies within Dolohov's ranks if there are any who could be swayed, by appealing to their sense of self - preservation or better nature.