A plot twist might be that when Naruko goes back in time, she accidentally alters the timeline in a way that creates a whole new set of problems. Like she could stop someone from dying, but that person then becomes a dictator in the future. Or she could find that the time - travel was actually a trap set by an enemy who wants to use her to rewrite history for their own evil purposes. It could also be that she goes back in time and discovers she has a different chakra nature than she thought, which completely changes how she approaches her ninja training in the past.
One common plot twist could be that Naruko discovers she has the power to change not only her own fate but also the fate of the entire village. For example, she might prevent a major disaster that originally happened in the past. Another could be that she finds out a hidden truth about her family or a powerful jutsu that was lost in time. Maybe she realizes that a person she thought was an enemy in the present was actually a friend in the past and has to figure out how to reconcile that in the future.
Often, a plot twist in Naruko goes back in time fanfiction is related to relationships. She might go back and find out that her parents' relationship was much more complicated than she knew. For instance, her father might have been involved in some sort of secret mission that affected their relationship. Or, she could find that a character she has a crush on in the present has a completely different personality in the past, which makes her question her feelings. There could also be a plot twist where she realizes that she is related to a powerful and mysterious clan that was erased from history, and this new knowledge changes her entire perspective on her identity.
Well, sometimes in these fanfictions, a plot twist might be that Sirius goes back in time and discovers a hidden truth about his family. Maybe he finds out that there was a secret alliance or a hidden enemy within the Black family that was influencing events all along. This could completely change his perception of his family's past and his place in it. Also, he could go back in time and end up being involved in a different kind of magic that was lost in his original time, like an ancient form of magic that has the power to either save or destroy the wizarding world.
Often, Dean will go back in time and accidentally change something small that has huge ripple effects on the future. Like he might save someone who was supposed to die, and then that person ends up causing a lot of chaos in the future that Dean has to fix. This creates a cycle of trying to set things right again. Another plot twist could be that when he goes back, he meets an alternate version of himself or his loved ones that are very different from what he knows, and he has to figure out how to deal with them.
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 possible plot twist could be that when they go back in time, they accidentally change something that has a huge impact on their future relationships. For example, Naruto might unknowingly prevent Sasuke from leaving the village in the past, which could completely change how they interact in the present they return to. Another could be that they find out a hidden truth about their parents or the village's past that was covered up, like a secret alliance that their predecessors were involved in.
One possible plot twist could be that Katniss goes back in time and prevents the Hunger Games from ever starting. Maybe she meets the people who first came up with the idea and manages to change their minds. Another could be that she goes back to a time before her father died and is able to save him, which would completely change her family's situation and her own personality development. A third plot twist might be that she goes back to a crucial moment in the Games and alters the outcome in a way that surprises everyone.
Maybe he goes back in time and meets a younger version of his enemy. Instead of fighting right away, he tries to understand what made the enemy turn bad in the first place. This changes the whole future dynamic between them when he returns to his own time. He might find out that there was a misunderstanding that led to all the hatred.
One possible plot twist could be that Oliver goes back in time and accidentally changes something that makes his friends turn into enemies in the present. For example, he might prevent an event that was crucial for the formation of their friendships. Another could be that he meets a younger version of himself and has to convince that version to make different choices without revealing too much about the future. It could also be interesting if he goes back to a time when his city was in a different state, like before the rise of a major villain, and he has to stop that villain from ever emerging in the first place.
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.
One popular plot twist could be Killua going back in time and accidentally changing something that has a huge impact on his relationships. For example, he might prevent himself from meeting Gon in the first place, and then has to figure out how to get their friendship back on track. Another could be that he goes back to a time when a great evil was just starting, and he has to stop it before it gets out of hand, which completely changes the future he knew.