Legolas would be both angry and confused. Angry because he has been unjustly kidnapped, and confused as to why the dwarves would target him. He would keep his wits about him though. He might start to observe the dwarves' behavior, their routines, and any weaknesses in their security. And he would most likely be thinking of ways to outwit them, perhaps by using their own pride or greed against them.
He would probably try to reason with the dwarves. Legolas is not one to jump into a fight immediately. He might try to explain that there is no need for such hostility and that elves and dwarves can resolve their differences in a more civilized way. If reasoning fails, he would then start to look for ways to break free from his bonds and overpower his captors using his elvish agility and archery skills.
In such a fanfiction, perhaps the dwarves might try to use Legolas as a bargaining chip. They could be after some elvish treasure or secrets. Maybe they want to exchange him for some powerful elvish weapon.
It could be an orc warband. Orcs have always been enemies of the elves, and they might see Legolas as a valuable captive either for ransom or to torture. Another possibility is a rogue wizard. Wizards who have turned to the dark side often seek powerful beings to experiment on, and Legolas, with his elven magic and skills, would be an interesting subject.
He would likely be initially shocked but then filled with a sense of protectiveness. Legolas is a noble elf, and he would do everything in his power to keep the OC and the unborn child safe. He might start to plan for their future, thinking about where they could live and how he could provide for them.
Orcs would be a likely kidnapper. They have a long - standing enmity with the elves, and Legolas being an important elf, would be a valuable captive. They could either want to torture him for information or use him as a bargaining chip with the elves.
At first, Legolas could be defensive. He might feel that the fellowship will treat him differently now. But as they show acceptance, he could gradually open up more about his life as a prince. He might share stories of his elven kingdom, its beauty and its traditions. And he would probably become more determined to uphold the honor of his title while still being a loyal member of the fellowship, using his position to help the group in any way he can, whether it's through his combat skills which might be enhanced by his royal training or his knowledge of elven lore.
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.
One idea could be that Legolas is kidnapped by an old enemy of the elves. This enemy might want to use Legolas as a bargaining chip to get some powerful elven artifact. Another plot could involve a powerful dark magic user who kidnaps Legolas to drain his life force which is believed to be very strong due to his elven heritage. A third option is that he is kidnapped by a group who mistakes him for someone else who has great value to them.
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.
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.