It would change the story a great deal. Since Pettigrew was a Death Eater and a key part of Voldemort's resurrection plan. If Harry brings him back during the 3rd task, he might be able to prevent some of Voldemort's future moves. Maybe Harry could get Pettigrew to testify against the Death Eaters, which would be a major shift in the power dynamics between the good and the bad in the wizarding world.
The overall story arc would be completely different. Harry bringing back Pettigrew means that there's a chance to get insider information on Voldemort. Pettigrew could be used to find out where Voldemort is hiding or what his next big move is. It might also lead to a different perception of Snape, as Pettigrew could potentially clear up some of the misunderstandings about Snape's actions that were related to Pettigrew's own actions in the original story.
Well, it could drastically change things. For one, Pettigrew's knowledge of Voldemort's plans would be a huge factor. Harry might use Pettigrew to expose more about Voldemort's return, which could lead to a quicker response from the wizarding world. Also, it could change Harry's relationship with Sirius, as Pettigrew was the key in Sirius' false imprisonment.
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.
The teachers would likely be very cautious. Professor McGonagall might be extremely strict and keep a close eye on Pettigrew. She would be worried about the safety of the students. Ron would probably be very angry at Harry at first. He has a strong hatred for Pettigrew because of what he did to his family. Hermione, on the other hand, would be more rational. She would try to analyze the situation and see if there is any benefit to Pettigrew being back at school.
Well, it can change the relationships in the story. Harry's relationship with Sirius, for instance, might not be as father - like as in the original. Since Lily is back, Harry has his real mother, and Sirius may take on a different role. Moreover, it can also affect the power balance. With Lily's return, the Order of the Phoenix could have a stronger magical force at their disposal, potentially changing the outcome of battles.
If Bellatrix was Harry's mother in this fanfiction, the whole plot would be a mess. Harry would be born into a family of pure - blood maniacs. His magical education would likely be focused on the dark arts rather than the normal curriculum at Hogwarts. His relationships would be warped. He may not have the same friends like Hermione and Ron. And his relationship with Voldemort would be extremely complex, as Bellatrix was one of Voldemort's most loyal followers. It would be a story full of moral and ethical dilemmas for Harry.
Well, if James Potter survived, it would completely change the backstory of Harry Potter. For one thing, Harry might have grown up with his father, which would have meant a very different childhood for him. He wouldn't be the orphan raised by the Dursleys. Also, James Potter was a talented wizard, so he could have been a major influence on Harry's magical education from a very young age. This would likely make Harry even more powerful and confident earlier on. And the fight against Voldemort would have been different too, as James would have been another powerful force against the Dark Lord right from the start.
In this fanfiction, the overall story arc might shift towards a more collaborative or parallel development of the two characters. Instead of the chase being a central plot point, the story could explore how Zuko and Aang both contribute to the peace and balance of the world in their own ways. Maybe they end up working towards the same goal from different angles. For example, Zuko could be reforming the Fire Nation from within while Aang is spreading the teachings of the Air Nomads. This would create a more complex and multi - faceted story compared to the original where the chase was a significant part of the narrative.
It can change the direction of Harry's character development. Instead of following a more traditional path of family - building, he has to find new meaning in his life. This could lead to him becoming more involved in mentoring young wizards or taking on more dangerous missions that he might have avoided if he had a family to think about.
Well, it can completely change the story arc. Since Harry is a central figure, if he's uncaring, the whole fight against Voldemort could be affected. He may not be as motivated to seek out Horcruxes or train for battles.
Well, it completely changes the nature of the magic - based world. Usually, the battle between Harry and Voldemort is about magic spells and wizardry. With a gun, it brings in a Muggle weapon, which might make the wizarding world seem less special. It could also change the way other characters view Harry. Some might see him as a radical for using such an un - wizard - like method.
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.