Maybe Harry decides to use Pettigrew to expose the truth about Voldemort's return. By presenting a living Death Eater who was involved in Voldemort's plot, he could convince the wizarding community that the Dark Lord is indeed back. This would also clear Sirius Black's name in the process.
Another consequence could be that within the fanfiction, Pettigrew's capture leads to some sort of magical investigation. Wizards might try to extract information from him about other Death Eaters, their plans, and any hidden secrets. This could be a dangerous process as Pettigrew might have been given spells or enchantments to prevent him from revealing too much.
One possible consequence could be that he is immediately sent to Azkaban. Since he's a known traitor, the wizarding world would want to punish him severely for his crimes, which include betraying the Potters and framing Sirius Black.
Often, Harry catches Pettigrew by using his invisibility cloak. He sneaks up on Pettigrew and then uses a stunning spell. It's a simple yet effective method that is often used in fanfictions as it plays on Harry's resourcefulness.
Harry might become more confident. Capturing Pettigrew on his own or with his friends shows his growth as a wizard. He's no longer just the boy who survived Voldemort's attack but a capable hero who can bring a criminal to justice.
Harry might face a lot of criticism. The wizarding community might think he's being naive by bringing back Pettigrew. There's also the risk that Pettigrew could double - cross him. After all, Pettigrew has a history of betraying those who trust him. This could put Harry in a very difficult situation, especially if Pettigrew lies about Harry or tries to frame him for something.
Definitely Hermione and Ron. Hermione would use her intelligence to analyze the situation and come up with a plan. Ron would be the more impulsive one, ready to jump into action. Sirius Black could also be involved. Since he has a history with Pettigrew, he might have some insights into Pettigrew's actions and be able to help in the search for Harry. Also, the Weasley family in general might get involved as they are close to Harry.
There might be new witches and wizards who have heard of his story. They could be either fascinated or disgusted by his past deeds. He may also run into future versions of Hogwarts professors. They would probably be very different from the ones he knew, with new teaching methods and different personalities.
One good 'Harry Capture Pettigrew' fanfiction could be 'The Capture at Hogwarts'. In this fic, Harry uses his quick thinking and newfound magical abilities to outwit Pettigrew. It shows an exciting chase through the castle corridors.
If Peter Pettigrew was caught, it could have completely changed the course of the story. Maybe Voldemort's plans would have been foiled earlier.
There are fanfictions that explore Peter Pettigrew's early days at Hogwarts. Maybe he was once a more innocent boy who got influenced by the wrong crowd. For example, a story could show how he first met James, Sirius and Remus and how his insecurities led him down the path of eventually becoming a Death Eater.
In some 'Harry Kidnapped by Pettigrew' fanfictions, one interesting plot development could be Harry's struggle to escape. He might use his wits and the little magic he can muster in captivity. For example, he could try to communicate with his friends through magical means that Pettigrew doesn't suspect. Another aspect could be Pettigrew's motives. Maybe he's being blackmailed by some dark forces to kidnap Harry, which adds a layer of complexity to the story.
Yes, there might be such fanfictions out there. Fanfiction writers often explore alternative storylines, and the idea of Pettigrew turning on Voldemort and killing him is an interesting and unexpected twist. It could involve Pettigrew having a change of heart due to some complex reasons, like realizing the true evil of Voldemort's ways or having a personal vendetta against him that overrides his loyalty.