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.
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.
Since the only thing we know is that Pedro tells a story, he could be from any background. He could be a young boy who loves to make up stories, or an old man with a wealth of life experiences to draw from for his stories. Maybe he's an immigrant with unique stories from his homeland.
Since we have no information about the story Pedro tells, it could be anything. It might be a fairy tale like Cinderella, or it could be a story from his own life experiences. Maybe it's an adventure story about a brave knight.