The kidnapped character might first show fear, especially if they don't understand Spock's motives. But then, they could start to analyze the situation. If they are a scientist or an engineer, they might try to use their skills to find a way out. They could try to disable the ship's systems that Spock is using to keep them captive. And if they have some knowledge of Vulcan culture, they could try to appeal to Spock's sense of honor and loyalty to Vulcan values, perhaps by reminding him of the importance of non - aggression and respect for life.
Naruto might be initially confused. He trusts Tsunade, so being kidnapped by her would be completely unexpected. He would probably start by asking her why she's doing this.
Sakura would probably be initially terrified. She would try to use her medical ninjutsu skills to defend herself or at least slow Itachi down. If she realizes she can't overpower him physically, she might try to talk to him, asking him why he's doing this.
She would be terrified at first, but quickly gather her wits. Hermione is very intelligent, so she would likely start observing her surroundings, looking for any possible means of escape or a way to send a signal to her friends.
In a Giyuu x Shinobu fanfic, the setting and plot can vary widely. Some might be set during the main events of the Demon Slayer universe, with them facing demons together. Others could be more of an alternate universe story, where they meet under different circumstances, like in a modern - day high school AU. The fanfic could also delve into their backstories and how those experiences shape their relationship. For instance, Shinobu's past with her sister could play a role in how she opens up to Giyuu, and vice versa for Giyuu's own traumas.
I would recommend 'Whispers of the Heart' for Giyuu x Shinobu fans. This fanfic focuses on their unspoken understanding. It's full of small moments that build up their relationship, like when Shinobu leaves a small flower on Giyuu's doorstep as a sign of her care. Also, 'Shadows and Sunlight' is worth checking out. It has a great plot that involves them having to go on a secret mission together and how that journey changes their relationship from colleagues to something more intimate.