Maybe it's a rogue wizard. Wizards can be unpredictable, and one with a grudge against the elves or a thirst for power might kidnap Legolas. He could think that Legolas has some sort of magical essence that he can use for his own dark magic experiments.
Well, perhaps it could be about a dark sorcerer who wants to use Legolas for some evil magic. Maybe he's kidnapped to be a sacrifice to summon an ancient and powerful being.
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.
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.
It could be a former patient of Kaoru's who has some mental issues. He might have misinterpreted Kaoru's care as something more and when she didn't reciprocate in the way he wanted, he decided to kidnap her.
In 'Clark Kidnaped Smallville Fanfiction', it could be Brainiac. This super - intelligent being might see Clark as a valuable specimen to study and kidnap him for that purpose. Also, a group of government agents who are afraid of Clark's power and want to keep him under control could be the kidnappers. They might think that by kidnapping him, they can find a way to neutralize his abilities. Additionally, a powerful witch or warlock from Smallville's supernatural side could kidnap Clark to use his powers for their dark magic.
It could be an old enemy of Keith's, someone from his past who has a vendetta against him. Maybe a former rival from his days in the military academy who has now turned to more devious means.
In some creative fanfiction, it could be an alternate version of Spiderman himself from a different dimension. This Spiderman has gone bad and kidnaps a fan from our dimension as part of some grand, dark plan that involves crossing dimensions and causing chaos.
A power - hungry nobleman from a neighboring land could be the kidnapper. He might believe that by having Rapunzel in his possession, he can gain some sort of political advantage or use her as a bargaining chip against her kingdom.
It could be Orochimaru. He's always been interested in obtaining powerful individuals for his experiments, and Naruko with her unique abilities would be a prime target.
It could be a new villain that has emerged, someone who is jealous of Gohan's power and wants to make it his own. This villain might be from a far - off planet and has heard of the Saiyan legend.