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.
After the initial shock and anger, Stiles could become determined. He might decide to prove his worth and innocence on his own. He could start his own investigation into whatever led to Scott's decision, with the goal of getting back into the pack and clearing his name.
One possible reason could be a misunderstanding. Maybe Stiles did something that Scott misinterpreted as a betrayal of the pack. For example, if Stiles made a deal with an enemy without Scott's knowledge, even if it was to protect the pack in the long run, Scott might see it as a breach of trust and decide to kick him out.
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.
Stiles might be initially shocked. He would probably feel betrayed since he thought of the pack as his family. He could go into a state of denial at first, not believing that they would actually kick him out.
It becomes strained. Trust is broken, and Stiles may start to distance himself from Scott. He might not believe in Scott's words or actions anymore, and there will be a lot of tension between them.
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.
Scott would be extremely worried and immediately start planning a rescue mission. He'd be angry at Theo for targeting Stiles and would use his alpha powers to try and track him down. He might also call on the rest of the pack for help, like Lydia, who could use her banshee powers to sense if Stiles was in danger or where he might be.
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.
It could be that the author of the fanfiction wants to create some conflict. Stiles might hate Scott because Scott has something that Stiles envies, like popularity or a special ability that seems to overshadow Stiles. So, the author uses this emotion to drive the plot and make the story more interesting.
The other characters might initially be confused. They could wonder why Stiles is suddenly absent and start to question if they did something wrong. Some characters may feel a sense of loss, especially those who were close to Stiles in the pack. They might miss his input during the meetings as he often had unique perspectives.