One possible plot twist could be that when Harry goes back, he discovers that Snape's situation is far more complex than he initially thought. Maybe Snape was involved in some secret mission that put him in danger, and Harry's interference actually endangers the entire wizarding world in unexpected ways. For example, Snape might be on the verge of uncovering a new dark magic plot that Harry's presence disrupts.
Well, perhaps Harry realizes that in order to save Snape, he has to make a deal with some dark forces. This could lead to a moral dilemma for Harry as he struggles between saving Snape and not getting involved with the wrong side. Also, it could be that when Harry goes back, he finds out that Snape's personality is very different from what he knew, and this new understanding changes how he tries to save him.
One possible plot twist could be that Snape, in his attempt to save Harry, accidentally changes the entire future of the wizarding world. For example, he might prevent Voldemort from ever rising to power in the first place, which would mean that all the relationships and events that we know from the original story would be completely different. Another plot twist could be that Snape discovers that saving Harry is not as straightforward as he thought. Maybe there are dark forces at work that are trying to stop him from changing the past, and he has to fight against them while also trying to protect Harry.
Well, perhaps when Fred goes back, he discovers that the danger to Harry is much more complex than he initially thought. There could be a traitor among the people he thought were allies in the past. Also, Fred himself might get stuck in the past and has to find a way to get back while still ensuring Harry's safety. Maybe the time - traveling magic is being manipulated by a hidden enemy, and Fred has to figure out who and how to stop it to save Harry.
One possible plot twist could be that when Lily goes back, she discovers that saving Sev is far more complicated than she thought. Maybe there are forces in the past that are determined to keep the original timeline intact. Another twist could be that in her attempt to save Sev, she accidentally changes something else in the wizarding world for the worse.
One possible plot twist could be that when Luffy goes back, he discovers that Ace's fate is more intertwined with the World Government's secrets than he thought. Maybe Ace was targeted not just because of his bloodline but because he knew something dangerous. Another twist could be that in the past, Luffy has to team up with unexpected allies, like some of the former enemies of the Straw Hats, to save Ace. And perhaps, his time - traveling disrupts the timeline in a way that creates new threats not only to Ace but to the entire world of One Piece.
One possible plot twist could be that when they go back in time, they accidentally change something that has a huge impact on the present. For example, they might prevent the sorting hat from putting them in their original houses. This could lead to a completely different dynamic at Hogwarts, with different friendships and rivalries forming.
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.
Well, perhaps Lilly realizes that Sev is in some sort of danger in the past that leads to a tragic end in the future. So she uses a magical device or spell to travel back in time. Once there, she has to find Sev among all the chaos and danger. Maybe she has to disguise herself to fit into the time period. Then she'd try to prevent the event that would have doomed Sev.
One possible plot twist could be that Jon Snow goes back in time and accidentally changes something that leads to a completely different future for the Stark family. For example, he might prevent Ned Stark from going to King's Landing, which would change the power dynamics in Westeros entirely.
He might use some powerful magic artifacts. For example, the Time - Turner, if he can get his hands on an even more powerful or modified version of it. This could allow him to bypass some of the normal time - travel restrictions.
Snape's character development could take a very different turn. He may start to value life more, not just Harry's but also those around him. In the original, his focus was mainly on his own pain and his loyalty to Dumbledore. But going back in time, he realizes that every action he takes can have a huge impact on the future. This could lead to him becoming a more empathetic character. He might also become more of a hero in the eyes of others, which is a big change from his somewhat villainous reputation in the original story. He could start to see himself in a new light and strive to be a better person not just for Harry's sake but for the sake of the entire wizarding world.