There's also the idea of preventing certain historical events from happening at all. Maybe a time traveler tries to stop the rise of Hitler before he gains too much power. This would involve interfering with the political and social situations in Germany in the early 20th century.
One idea could be a soldier from WW1 suddenly finding himself in the middle of a WW2 battle. He might use his old - fashioned combat skills in a new and more advanced war setting. For example, his experience with bayonet charges could be a shock to the modern - day soldiers he meets in WW2.
One interesting WW2 time travel fanfiction could be about a modern-day historian who travels back to WW2. They might use their knowledge of the war to change small events and see how it affects the overall outcome. For example, they could prevent a key intelligence leak that would have otherwise given the enemy an advantage.
One interesting plot could be a modern person traveling back to WW2 and using their knowledge of future technology to help the Allies in a covert way, like improving communication systems. Another could be a time traveler trying to prevent a particular tragic event during the war, such as the bombing of a certain city. And there might be a plot where the time traveler has to adapt to the harsh wartime conditions and forms unexpected friendships with soldiers on the front line.
One interesting concept is the butterfly effect. In time travel fanfiction, a small change in the past can lead to huge differences in the future. For example, a character might go back in time and accidentally prevent their parents from meeting, which would change their own existence completely. Another concept is time loops, where a character is stuck repeating the same period of time over and over until they figure out how to break the loop. Also, alternate timelines are often explored, showing how different choices in the past can create entirely new versions of the present and future.
In some gaara time travel fanfiction, Gaara might travel to the future and see how his village has developed. He could be shocked by the new technology or the changed social structure. This could lead to him bringing back ideas to improve his own time.
One interesting concept could be how Kirk and Spock's relationship evolves differently due to time travel. For example, if Kirk travels back in time and meets a younger Spock, he might see a different side of him. Maybe Spock is more impulsive in his youth, and Kirk has to adapt to this new version while still being in love with the future Spock he knows.
Another concept is meeting alternate versions of characters. When the Flash travels through time, he might encounter different versions of himself or his friends. This can lead to some really cool character development and interactions, like an older, more jaded Flash meeting his younger, more idealistic self and learning from each other.
Well, time loop is a cool concept in it. Imagine a character in shinachiku time travel fanfiction getting stuck in a time loop where they keep repeating the same day or event over and over again. They have to figure out what's causing the loop and how to break it. It's a great way to build suspense and explore the character's growth as they try different things each time the loop repeats. Also, the idea of time travel being a form of punishment or redemption can be interesting. A character who has made mistakes in their own time might be sent back to correct things, either for their own salvation or as a form of atonement for their actions.
One interesting concept could be the alteration of historical events. In obikaka time travel fanfiction, characters might go back in time and accidentally or purposefully change a significant event, which then has a ripple effect on the future. For example, a character could prevent a key invention from being made, leading to a completely different technological landscape in the present they return to.
One interesting concept is how characters might change the course of major events. For example, if a character could go back in time and prevent the death of Ned Stark, it would completely alter the political landscape of Westeros. Another concept could be the discovery of magic related to time travel that was previously unknown in the original series. It could introduce new powers and factions vying for control over this new form of magic.