In some fanfictions, Stiles might also play it cool. He knows that showing fear could be a weakness that Peter will use against him. So, he could act nonchalant, as if he's not bothered by the kidnapping at all. He might start making sarcastic remarks to Peter, which could either annoy Peter or make Peter respect him in a strange way. This reaction can add an interesting dynamic to the story, as it throws Peter off his game and makes their interactions more unpredictable.
On the other hand, Stiles is also known for his quick thinking. He might start to try and bargain with Peter. He could offer to help Peter in some way if Peter lets him go. For example, if there's a problem in the supernatural community that Peter is facing, Stiles could say he'll use his human ingenuity to solve it. Also, Stiles could be angry. He might start shouting at Peter, calling him out on his actions, and trying to make Peter see how wrong this is.
Stiles usually reacts with a mix of fear and defiance. He's afraid because he's in a dangerous situation, but his strong - willed nature makes him defiant. For example, in many fanfictions, he'll shout at Peter, trying to show that he won't be easily broken.
Stiles might initially be shocked. He has been a part of the pack for a long time, and Scott kicking him out would be completely unexpected. He could stand there in disbelief, unable to process what has just happened.
It could also be for revenge. Perhaps Stiles or someone associated with him has wronged Peter in the past within the context of the fanfiction story. So, Peter kidnaps Stiles to get back at him or those related to him. Another reason might be that Peter is being controlled by some other force. There could be a dark entity manipulating Peter's actions, and it makes him kidnap Stiles for its own sinister purposes.
At first, it might be a tentative alliance. Stiles could be initially drawn to Peter for his knowledge. Peter, seeing Stiles' potential, starts to include him more in his plans. As time goes on, they might develop a mutual understanding. Stiles begins to trust Peter more and more, and Peter starts to value Stiles not just for his help but also as a friend or something more.
Some members of the pack might be angry at first. They could see his leaving as a betrayal, especially if they are in the middle of a difficult situation and rely on him in some way.
It could be that Stiles is in some kind of danger, perhaps from another supernatural being. And he goes to Peter because Peter has certain powers or knowledge that could protect him. For example, Peter might know how to defeat a particular enemy or how to get out of a tricky situation involving magic or some other supernatural element.
Peter would probably be scared at first. He's just a kid, after all, and being kidnapped by a powerful being like Thanos is terrifying. But he would also be defiant. He has a strong sense of responsibility, so he might try to find a way to escape on his own.
Scott would be the most likely one. He's Stiles' best friend and the True Alpha. He would never let the Alpha pack harm Stiles and would go to great lengths to rescue him.
Some of his friends might be really surprised. Scott, for example, might be a bit worried that Stiles' vampire obsession could lead him into dangerous situations. Lydia, on the other hand, could be more intrigued and might want to know more about the fanfiction. She might see it as an interesting intellectual pursuit.
There could be other members of Peter's pack such as Derek. Derek often plays an important role in stories related to packs. He might be initially skeptical of Stiles being part of the pack.