The kidnapped character could use their own hidden jutsu skills to break free. For example, if they have a teleportation jutsu they've been hiding, they could use it when Sasuke is distracted. Another way is to appeal to Sasuke's emotions. If they can remind him of his better nature or a past event that made him more empathetic, he might let them go.
Perhaps Sasuke has been influenced by some dark force. This force could be manipulating him into believing that Naruto is a threat to his goals. So, he kidnaps Naruto to either stop him from interfering or to convert him to his side. It could lead to a very intense struggle within Naruto to resist Sasuke's influence.
In many Sasuke - Sakura fanfictions, a kidnapping plot can add a lot of drama. If Sasuke kidnapped Sakura, it could be due to various reasons. Maybe he was influenced by some dark power that made him lose his rational thinking and see Sakura as a key to something he wants. This kind of plot often leads to a series of events where Sakura has to face her feelings towards Sasuke in a very extreme situation, like trying to understand his motives while also being scared for her own safety.
One possible plot could be that Sasuke has a hidden agenda. Maybe he believes Naruto is in danger from a new, unseen enemy in the ninja world. So, instead of explaining his reasons to Naruto, he kidnaps him to keep him safe in a secret location. However, this action might be misinterpreted by their friends, leading to a search and rescue mission.
Sasuke would likely be very guarded in his captivity. He would not show all his cards, even if Orochimaru tries to get information out of him. He may act cold and distant, only speaking when necessary. Inside, he's probably thinking about ways to turn the situation to his advantage. He could also be biding his time, waiting for the right moment to make his move. Given his goal of getting stronger to avenge his family, he might consider using Orochimaru's resources, but he would never fully submit. He's always aware of the risks and the fact that Orochimaru could turn on him at any moment.
Kakashi would be deeply concerned. Given his relationship with Sasuke, he'd feel a strong sense of duty to save him. He'd use his extensive network of contacts within the ninja world to try and find out where Sasuke has been taken. He might also reflect on his past training with Sasuke and how he can use that knowledge to anticipate the kidnappers' moves. He'd be ready to face any danger or obstacle in his path to rescue Sasuke. And he'd be constantly thinking about Sasuke's safety and well - being during the whole process.
Sasuke could also be confused. He has always had a mix of emotions towards Itachi, including love, hate, and envy. Being kidnapped by him would add another layer of confusion. He might wonder if Itachi has some new plan or if he's finally going to reveal some long - hidden truth. So, he might hold back on his full - fledged resistance and wait to see what Itachi has to say.
One plot idea could be that Sasuke kidnaps someone he believes has information about a hidden enemy. He then has to deal with the moral implications as he realizes the person is innocent. Another could be a love - driven kidnapping, where Sasuke kidnaps someone he secretly loves but is too conflicted to show it in a normal way. And perhaps a third idea is that Sasuke is forced to kidnap someone under a mind - control spell and has to fight against the control to free the victim.
One common plot twist could be that Sasuke actually planned to be 'kidnapped' to some extent. He might have wanted to gain power from Orochimaru in a more secretive way. Another could be that Naruto and his friends discover Orochimaru's lair much sooner than expected, leading to a premature rescue attempt. And sometimes, Orochimaru may not be the real mastermind behind the kidnapping, but rather a pawn of a more powerful enemy.
If Sasuke kidnapped Naruto, it could initially seem like a huge betrayal. However, Naruto is known for his ability to forgive. He might see this as Sasuke still caring about him in his own, twisted way. This could make their relationship more complex, with Naruto constantly trying to reach out to Sasuke and Sasuke struggling with his own emotions and reasons for the kidnapping.