In this fanfiction, a really cool plot twist might be that the big three go back in time and find out that they are not the first ones to have done so. There are other hidden forces or characters who have been manipulating time all along, and they now have to deal with these new adversaries while also trying to fix whatever they went back in time to fix.
One interesting plot twist could be that when the big three go back in time, they find out that their actions in the past have unexpected consequences on their present selves. For example, a small decision they make in the past ends up changing their relationships with each other in the present in a major way.
Perhaps a plot twist could be that they go back in time to prevent a certain event from happening, but in the process, they discover that the event was actually necessary for their own growth and development. So, instead of preventing it, they have to find a way to make it happen in a different way. This would add a whole new layer of complexity to the story.
The 'big three' are likely to be the main characters. However, without more context, it's hard to say exactly who they are. They could be three powerful heroes or villains from a particular fictional universe.
One interesting plot twist could be that Thor goes back in time and accidentally changes something that makes him lose his powers. For example, he might prevent the event that led to him getting Mjolnir, and then has to find a new way to be a hero without his trusty hammer. Another could be that he goes back and meets a younger version of Loki who doesn't yet hate him, and he has to figure out how to keep it that way so that their relationship in the future is different.
One interesting plot idea could be that Hikaru goes back in time to the era when the Go masters of old were alive. He then challenges them to games of Go, learning new strategies and techniques that he brings back to his own time. This could lead to him becoming an even greater Go player and changing the way modern Go is played.
One possible plot twist could be that Percy meets his own parents at a different time than expected. For example, instead of seeing his mother as he knew her, he might encounter her as a young girl. Another twist could be that Kronos has some ulterior motive for sending Percy back that Percy doesn't initially realize, like changing the course of events to actually benefit Kronos in the long run. Maybe Percy discovers that by changing certain events in the past, he's unknowingly setting up a different future that Kronos can manipulate more easily.
One interesting plot twist could be that Harry goes back in time and accidentally changes the sorting of some of the characters. For example, Draco Malfoy could end up in Gryffindor instead of Slytherin, which would completely change their relationship and how events unfold in the wizarding world.
One interesting plot twist could be that when Lucy goes back in time, she discovers that her family has a much darker secret than she ever knew. Maybe they were involved in some sort of magic that was considered forbidden in the past. Another could be that she accidentally changes the future in a way she didn't expect, like making her friends not become the people she knew them as. And perhaps she finds out that an enemy in the present was actually once an ally in the past, and she has to figure out what went wrong to turn them into an enemy.
One interesting plot twist could be that Naruto, with his knowledge of the future, tries to prevent certain tragedies but ends up causing new ones. For example, he might try to save a character too early and disrupt the natural flow of events, leading to unforeseen consequences.
Perhaps in the fanfiction, when time is turned back, Hermione decides to focus on different areas of magic. Instead of being all about books and rules, she starts to explore dark magic in order to stop Voldemort before he rises. This could put her at odds with Harry and Ron. Also, if time is turned back far enough, Dumbledore could be a student again. He might make different choices that change the whole wizarding world's future, like not getting involved with Grindelwald, which would have a huge impact on the events leading to Voldemort's rise.
Well, perhaps in the fanfiction, when they go back in time, Harry and Daphne end up changing the Hogwarts houses. Since they know different things about the students, they might influence the sorting hat. This could lead to new friendships and rivalries, completely altering the social dynamics at Hogwarts.
In 'Harry go back to the marauders time fanfiction', a really engaging plot point is Harry's internal struggle. He has to decide whether to interfere with the past or not. On one hand, he might be tempted to save his parents from their tragic fate. But on the other hand, he knows changing the past could have huge consequences. This conflict within him can drive the whole story. Also, his relationships with the Marauders are key. How does he fit into their friendship? Does he become a new member of their group? Or is he more of an outsider trying to help from the sidelines?