Well, it's a rather specific kind of fanfiction. I haven't come across one with that exact plot myself. But if you're into Teen Wolf fanfiction, you could join some Teen Wolf fanfiction communities or forums. There, you can ask fellow fans if they know of any such stories. They might be able to point you in the right direction.
I'm not sure specifically about 'peter spanks stiles' fanfiction. You could try searching on popular fanfiction websites like Archive of Our Own or Fanfiction.net. They have a vast collection of Teen Wolf - related fanfics, and you might find something that comes close to what you're looking for.
Archive of Our Own (AO3) is a great place to start. It has a large number of Teen Wolf fanfictions, and you might be able to find the 'peter spanks stiles' one there. Just use the search bar and type in relevant keywords.
Search on AO3. It has a vast collection of fanfictions. Use the character names 'Peter Hale' and 'Stiles' in the search bar and then look through the results. You might need to go through multiple pages to find what you're looking for.
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.
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.
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.
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.
One common theme is the exploration of their complex relationship. Since they have different personalities and backgrounds in the show, fanfiction often dives into how they interact and influence each other. Another theme is the supernatural elements. Given the nature of the show, stories might involve them facing supernatural threats together or having unique supernatural abilities related to their bond.