Naruto would probably first try to fight back. He's not the type to just go along with being kidnapped. He'd likely use his Shadow Clone Jutsu to create a distraction and try to escape.
Well, one possible plot twist could be that Kohana has a hidden motive that's not as evil as it seems at first. Maybe she's being controlled by a greater force and Naruto realizes this and tries to save her instead of just escaping. Another could be that Kohana is actually from a long - lost clan that has a prophecy related to Naruto, and the 'kidnapping' is a way to start fulfilling that prophecy.
In 'evil Kohana Naruto fanfiction', one characteristic could be that the Kohana village may be depicted with a darker side. For example, the village's leadership might be shown as corrupt or having ulterior motives. This can add a whole new layer of complexity to the Naruto universe we know.
Regular Naruto fanfiction usually follows the general themes and moral compass of the original series. But 'evil Kohana Naruto fanfiction' takes a turn. It flips the idea of Kohana being a place of good. In regular fanfic, we expect the village to be a positive force, but in this type, it's often the source of problems.
One possible motive could be love. In the fanfiction, female Naruto might be secretly in love with Sasuke and sees kidnapping as a way to keep him close. Another motive could be to prevent Sasuke from seeking revenge. She may think that by kidnapping him, she can stop him from going down a dark path that will lead to his destruction.
Sakura would be extremely worried. She would probably try to gather the other members of Team 7, like Sasuke and Kakashi, to go after them. Sasuke might be a bit more hesitant at first, but his loyalty to Naruto would eventually make him join the search. Kakashi, on the other hand, would be more strategic. He would try to figure out Minato's motives first and then plan the rescue mission accordingly.
Perhaps it's a personal grudge that Gaara has unknowingly held. Maybe there was an incident in the past where Naruto's actions had an indirect negative impact on someone Gaara cares about in Suna. Gaara's actions are often driven by his emotions and his past traumas. He could have bottled up this grudge without realizing it and finally decides to kidnap Naruto to get some sort of revenge or closure.
In the fanfiction, Naruto might use his shadow clone jutsu. He could create multiple clones to surround the kidnappers and disorient them. Then, while they are distracted, he could swoop in and rescue Moegei.
In some fanfictions, Hinata might kidnap Naruto for various reasons. Maybe she's desperate to get his attention or there's some misunderstanding that she thinks can only be resolved this way. However, this is a very uncharacteristic action for the usually shy and gentle Hinata in the original series.
Yes, there can be non - inappropriate fanfiction with a kidnapping theme in the Naruto universe. For example, a story could involve a character being kidnapped by an enemy ninja group not for any immoral reasons but as part of a strategic move in a political or territorial conflict. The story could then focus on the rescue mission and the growth of the characters involved in it.