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 probably be initially shocked and angry. She has always cared about Sasuke, and this betrayal would hit her hard. But she is also a strong - willed ninja. So, she would quickly gather her wits and start looking for ways to escape. She might try to use her knowledge of Sasuke's fighting style against him if she gets the chance.
Sakura could use her medical ninjutsu skills to create a distraction. For instance, she might make it seem like she's poisoned herself, causing Sasuke (or whoever is involved in the kidnapping) to get closer, and then she could attack and escape.
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.
Well, in such a fanfiction, Sakura might be used as a bargaining chip. The Akatsuki could try to exchange her for something valuable, like secret jutsu. Or they might want to extract information from her about Konoha's defenses.
A rogue shinobi who has a personal vendetta against Sakura or her friends. Maybe this shinobi blames Sakura for something that happened in the past and decides to kidnap her as revenge. He could be a powerful and unpredictable antagonist.
Another plot could involve Sakura being kidnapped by an enemy who wants to use her for her special abilities. This could lead to a story of her trying to escape on her own while also dealing with the kidnapper's demands and threats.
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.
Sakura being kidnapped could lead to a lot of character development in the fanfiction. Maybe she tries to escape on her own while Naruto and the others are on their way. She could use her medical ninjutsu skills to heal herself if she gets injured during the escape attempts. Meanwhile, Team 7 might also have to face some internal conflicts during the rescue operation, like differences in their strategies, but in the end, they will surely come together to save Sakura.
They might treat her harshly at first to break her spirit. But then, realizing her value, they could start to offer her deals, like freedom in exchange for her cooperation. However, Sakura is a tough character, so she'd likely resist their attempts.