One great 'deucalion kidnaps stiles fanfiction' is 'The Kidnapped' on FanFiction.net. It has an interesting take on how Stiles deals with being in Deucalion's clutches and the psychological drama that unfolds.
Survival is also a big theme. Stiles has to figure out how to survive in a dangerous situation with Deucalion. This could involve things like finding food, avoiding other threats in the place where he's held, and dealing with Deucalion's mood swings.
One popular 'derek kidnaps stiles fanfiction' is 'Kidnapped by the Alpha'. In this story, Derek has his reasons for kidnapping Stiles that are gradually revealed as the plot unfolds. It's full of mystery and a bit of a dark undertone.
I'm not sure of specific 'theo kidnaps stiles fanfiction' stories off the top of my head. But you can try searching on fanfiction platforms like Archive of Our Own. They usually have a wide variety of Teen Wolf - related fanfics that might include this plotline.
One great place to find Stiles x Deucalion fanfiction is on Archive of Our Own (AO3). It has a vast collection of fan - made stories with different themes and plotlines. Just search for the pairing, and you'll get numerous results.
The contrast between their characters. Stiles is a young, intelligent human, while Deucalion is a powerful and often menacing werewolf. Their interactions can be really interesting, like in some fanfictions where Stiles has to outwit Deucalion or they end up having to work together against a common enemy.
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.
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.
One common theme is the forced proximity. Since Derek kidnaps Stiles, they are forced to be close to each other. This often leads to a deeper understanding of each other and sometimes the development of romantic feelings.
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.
It could also be for power. Perhaps Stiles has some knowledge or ability that Theo wants to use for his own gain. In the show, Stiles was quite smart and resourceful, so Theo might kidnap him to get access to that intelligence or those skills. In some fanfictions, Theo might be trying to use Stiles as a bargaining chip to get something from the other characters like Scott or Derek.