Stiles' father could be a major character. He would be worried sick about his son and use all his resources to try and find him. Maybe he teams up with some of Stiles' friends like Scott or Lydia.
Scott, being Stiles' best friend, would surely be a main character. He would be determined to rescue Stiles and use his werewolf abilities to track Kate. He might also struggle with the moral dilemma of how far he's willing to go to save his friend.
There could be a new character introduced, like a detective who is also on Kate's trail. This detective might initially suspect Stiles' friends but then realizes they are on the same side. They could work together to stop Kate and rescue Stiles, adding an interesting dynamic to the story.
In this fanfiction, Kate might be working for a greater evil. She kidnaps Stiles to force him to do her bidding. Maybe she needs him to break into a secure location or decrypt some important information. Since Stiles is often portrayed as clever, she might think he can solve a problem for her.
He could use his intelligence to manipulate Kate. Maybe he convinces her that he is more useful to her if he is free, and she lets her guard down long enough for him to make a run for it. Also, he could have some hidden skills or knowledge that he uses to break free. Say he knows a spell or a code that unlocks his restraints or the door to his prison.
One common theme is betrayal. Kate often betrays Stiles' trust in these fanfictions, which leads to his emotional and sometimes physical hurt. This theme is central as it drives the conflict in the stories.
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.
Well, aside from Stiles, Scott is bound to be a central character. Their friendship is so strong that Scott would immediately start looking for ways to rescue Stiles. Derek Hale is another likely character. Given his past with the alpha pack and his relationship with Scott and Stiles, he would have a role to play. Then there's Allison. Her family's history with the supernatural means she has skills and knowledge that could be useful in rescuing Stiles. She could be involved in the search and rescue operation, using her archery skills and knowledge of the supernatural world to help out.
A good starting point could be a normal day in Beacon Hills. Stiles is going about his business, maybe on his way to meet his friends. Then, suddenly, Kate appears out of nowhere and grabs him. This sudden and unexpected event can immediately hook the readers. You could describe the look of shock on Stiles' face and the cold, determined look in Kate's eyes.
There's also 'Kate's Betrayal'. In this fanfic, Kate's actions towards Stiles are not only physically hurtful but also shatter his trust. It's a heart - wrenching read that really shows the darker side of their relationship. It's well - written with a lot of descriptive language to bring out the emotions.
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.
Another character he could interact with is Thor. Thor's otherworldly nature and his powerful abilities would be quite a contrast to Stiles. Maybe Stiles could help Thor understand some earthly concepts while Thor could teach Stiles about Asgardian culture and power.
There could be a tough drill sergeant who acts as a mentor and a source of conflict for Stiles. This character would be strict but fair, and would push Stiles to his limits.