Well, a really interesting plot twist might be that when Merlin travels back in time, he discovers that the future he thought he knew was all wrong. Maybe the events that led to Arthur's rise and fall were actually set in motion by a time - traveling sorcerer from even further in the future. He could also find that the people he thought were his allies in the past were actually working against him all along, which would completely change his view of history and his role in it.
Well, a really interesting plot twist might be that when Rick travels back in time, he discovers that time is actually a loop. So all his actions in the past were already pre - determined and he was just fulfilling his part in the loop. This could lead to a whole existential crisis for Rick as he realizes he may not have as much control as he thought. Or perhaps he goes back and finds out that an enemy from the future has already been manipulating events in the past to try and stop Rick from ever becoming the genius he is.
Perhaps Tony travels back to a time before a key technology was developed in his world. He then has to figure out how to recreate that technology with the limited resources of the past. This could lead to some really interesting interactions with the scientists of that era. Also, he might accidentally introduce some future concepts that are far ahead of their time, which could cause a stir among the intellectual community. And if he changes the development of this technology too much, it could have a huge impact on the future he came from.
One possible plot twist could be Naruto changing the past in a way that completely alters the future relationships. For example, if he prevents a certain event that led to a character's death, it could change the whole dynamic among the characters. Another twist could be that Naruto discovers that the past is not as simple as he thought, and there are hidden forces at work that he didn't know about in his original timeline.
One common plot twist could be that the end, when traveling back in time, accidentally changes something that has a huge ripple effect on the future. For example, they might prevent an important event from happening that was crucial for the development of a certain technology or the rise of a key character. Another plot twist could be that the end realizes they are not actually in their own past but in an alternate timeline. This can lead to a whole new set of challenges as they try to figure out how to get back to their own timeline or if they should even try to change things in this new one.
One possible plot twist could be Anakin going back in time and preventing his own fall to the dark side. He might use his knowledge of the future to avoid the events that led him to become Darth Vader. For example, he could avoid the temptation of Palpatine's offers. Another twist could be that his time - traveling disrupts the Force in unexpected ways, causing new alliances and enmities to form. Maybe he accidentally changes the course of other Jedi's lives, leading to a completely different galactic power structure.
One possible plot twist could be that Narukaka travels back in time and accidentally changes a small event that has huge, unforeseen consequences in the future. For example, preventing a minor meeting between two people that was supposed to lead to a great discovery.
One possible plot twist could be that Naruto and Jiraiya travel back to a time when the Uchiha clan was at its peak. This would put Naruto in a position to potentially prevent the Uchiha massacre. He could use his knowledge of future events and his skills to change the course of history for the better. Jiraiya, on the other hand, could discover secrets about the Uchiha that were lost over time.
One of the most interesting plot twists could be when a character from the original 'The Godfather' story travels back in time and accidentally changes a major event that alters the whole family's future. For example, if Michael Corleone went back and prevented his father from being shot, it would completely change the power dynamics and the family's path in the mafia world.
A great plot twist would be if Meredith time - travels to an alternate reality within the Grey's Anatomy universe. In this alternate world, all the relationships are different. For instance, she might find that she and Alex are married instead of her and Derek. This would completely shake up her understanding of her own life and the people around her. It could also lead to her trying to find a way back to her 'true' reality while also learning valuable lessons about her relationships and herself in this strange new world.
One exciting plot twist could be Octavia traveling back in time and accidentally changing a key event that led to the creation of the Ark. This would completely rewrite the history of the 100. Another could be her meeting a younger version of herself and trying to guide her without revealing her true identity. It would create a lot of internal conflict for Octavia as she sees her younger, more naive self.