One possible fanfic could start with Sakura out on a solo mission in a forest. Sasuke, who has been misled by some dark force, sees this as an opportunity to get Sakura for some unknown reason. He uses his ninja skills to quickly subdue her and takes her to a hidden cave. Sakura is shocked and tries to reason with him, but Sasuke seems to be in a trance. Meanwhile, Naruto and the others start to search for her when they realize she's missing.
It could be Orochimaru. He's always been interested in Sasuke and might see kidnapping Sakura as a way to manipulate Sasuke. He could use Sakura as a guinea pig for his experiments or as a bargaining chip to get Sasuke to come to him.
Well, one possibility could be that it's a dark fanfic where an enemy of Sakura kidnaps her to get to Sasuke. Maybe they want to use her as bait to lure Sasuke into a trap. Since Sasusaku is a popular pairing, the kidnapper might think that Sasuke would do anything to save Sakura.
It could be Orochimaru. He has always been interested in Sasuke and might kidnap Sakura to use her as bait to get Sasuke back under his control. He could be after Sasuke's power and think that by using Sakura, he can manipulate Sasuke easily.
Sakura could be kidnapped by Sasuke when she's on her way to deliver some important medical supplies. Sasuke, who is on a self - imposed mission that he believes requires Sakura's presence, takes her. For example, he might think she can heal a certain injury that he has. Sakura, being the strong - willed character she is, tries to escape at every opportunity during their journey to his hideout.
A possible plot for a 'Sasuke Sakura Kidnapped Fanfic' could be that a mysterious organization kidnaps Sakura. This organization is secretly researching the Sharingan and believes that Sakura, due to her close relationship with Sasuke, has some knowledge about it that they can use. Sasuke, of course, is enraged when he finds out. He embarks on a solo mission at first, but later realizes he needs the help of his friends. Along the way, we can explore the dynamics between Sasuke and Sakura, like how Sasuke regrets not being there to protect her, and how Sakura remains strong in the face of danger, believing Sasuke will come for her.
Naruto would be a likely candidate. He has a deep bond with Sakura and would never let her be in danger for long. He'd probably rush in without hesitation to save her.
She could also pretend to cooperate with Orochimaru at first. Gain his trust a little bit and then when he least expects it, make her move. Maybe she could ask Orochimaru for some tools or access to certain areas under the pretense of helping him with his work, but in reality, she is setting up her escape.
Sakura would be scared. She's in a dangerous situation with a powerful enemy. But she's also a strong - willed ninja. So she would be looking for ways to escape or at least hold her own until help arrives.
Well, in such a fanfic, perhaps Team Hebi kidnaps Sakura to use her as a bargaining chip against Konoha. They might want to exchange her for some valuable information or a powerful jutsu scroll. Another possibility is that they think Sakura has some special knowledge about a certain power source that they are interested in.