One possibility is that Gohan's friends and family, especially Goku, would immediately start searching for him. They would use all their powers and resources to track Vegeta's whereabouts. Goku might be enraged and ready to fight Vegeta to get his son back.
Another scenario could be that Vegeta is being manipulated by an outside force. This force might have convinced Vegeta that Gohan holds the key to something important, like a powerful energy source or a way to defeat a new and dangerous enemy. Vegeta, being prideful and believing he can handle the situation, kidnaps Gohan to figure out this mystery.
Perhaps Vegeta has a specific reason for kidnapping Gohan. It could be related to some sort of training regime he has in mind. He might see potential in Gohan and want to push him to new limits away from the influence of the others. So, he takes Gohan to a secluded place for intense training.
Next, Eren could try to escape. Given his strong will, he won't just sit there and accept being kidnapped. He might use his titan powers in a creative way to break free from Levi's clutches.
Well, one possibility is that Cloud's friends would immediately start a rescue mission. They might track Sephiroth's usual hideouts. Since Sephiroth is a powerful foe, they would have to be very strategic.
Perhaps Vegeta kidnaps Goku to get some secret training method from him. Vegeta is always eager to become stronger, and he might think Goku has some hidden knowledge that could help him surpass his limits. So he takes Goku to a secluded place to force the information out of him.
Maybe Vegeta wants to use Gohan as a bargaining chip. He could be in a situation where he needs to gain an advantage over the other Z - fighters. By kidnapping Gohan, he can force the others to meet his demands, like giving him access to some special training grounds or powerful artifacts.
Well, in a fanfiction where Captain Hook kidnaps Wendy, one possibility is that the Lost Boys come to her rescue. They might use their knowledge of the island and their unique skills to outwit Hook and his pirates.
In a fanfiction where Esdeath kidnaps Tatsumi, one possibility is that she tries to force him to join her side. She might use various means like threats against his friends or promises of power. Tatsumi, being a hero at heart, would likely resist. He could try to escape while also trying to figure out Esdeath's weaknesses to defeat her later.
Well, in a typical scenario, Sonic would probably rush to save Tails. He'd use his super speed to track Eggman's lair. Maybe he'd find some clues along the way, like a piece of Tails' fur or a gadget that Eggman accidentally dropped. Then, Sonic would face off against Eggman's badniks, defeat them one by one, and finally reach Tails. He'd free Tails and they'd escape together, with Eggman vowing revenge as usual.
Well, Naruto might use his Nine - Tails chakra to break free. He's a tough one. He could also try to outwit Orochimaru with his ninja skills. Maybe he'd pretend to be unconscious and then surprise Orochimaru when he least expects it.
Another scenario could be that Naraku has some ulterior motive for kidnapping Kagome. Maybe he wants to use her spiritual powers for his own evil purposes. He could try to corrupt her or force her to use her powers against Inuyasha and the others. But Kagome would resist with all her might, and her love for Inuyasha and her friends would give her the strength to hold out until they come to her rescue.
In a scenario where Orochimaru kidnaps Hinata, the Hyuga clan would surely get involved. They'd be outraged and use all their resources to find her. Orochimaru might be interested in Hinata's Byakugan for his experiments. He could try to extract its power or study it. But Hinata has been trained in the Gentle Fist style, so she might be able to hold her own against Orochimaru's minions for a while. And who knows, Sasuke might also get involved. He has his own history with Orochimaru and might see this as a chance to confront him again, especially if he realizes that an innocent like Hinata is in danger.