Perhaps a story where a Tudor figure gets a glimpse of the future through some magical means in the fanfiction. This could lead to them trying to prevent a future disaster or change their own fates in unexpected ways.
One interesting plot could be a character from modern times being transported back to the Tudor era and having to navigate the complex court politics. Maybe they accidentally change the course of history.
There might be a plot where a modern historian, a huge fan of the Tudors, goes back in time and tries to correct the historical inaccuracies they've always been frustrated about. They could get involved in relationships with Tudor nobles and influence the era in ways they didn't anticipate.
One interesting plot could be Ichigo going back in time and preventing certain tragedies that happened in the original story. For example, he might stop the death of a beloved character, which would then change the entire course of events and relationships in the Bleach universe.
Anne Boleyn is also very popular. Her tragic end and her role in the English Reformation give a lot of room for creativity in fanfiction. She can be portrayed as a strong - willed woman fighting against the constraints of her time.
One interesting plot could be Severus going back to his school days and trying to prevent certain tragedies. For example, he might try to stop the rift between him and Lily. He could use his knowledge of the future to avoid making the mistakes that led to their falling out. Another plot could involve him changing the course of events related to Voldemort's rise. Maybe he tries to expose Voldemort's plans earlier or influence key characters to oppose him more effectively. He could also go back to a time before he got involved with the Death Eaters and choose a different path entirely, which would then have a huge impact on the wizarding world as we know it.
One interesting plot could be Izuku going back in time and using his future knowledge to prevent certain tragedies. For example, he might stop the initial injury that All Might received, which could change the whole course of the story. Another plot could be him going back to his own childhood and being able to train better and earlier, thus becoming an even stronger hero. He could also use his knowledge of future villains to stop them before they become a major threat.
One interesting plot could be Snape going back and trying to prevent the death of Lily. He might use his knowledge of the future to change certain events that led to her demise. Maybe he would try to expose Pettigrew earlier or find a way to make James Potter more cautious.
Maybe in the fanfiction, Aang goes back in time and meets his past self. He then has to guide his younger self without disrupting the timeline too much. This could lead to some really cool moments of self - discovery for Aang, as he sees himself from an outside perspective and realizes how much he has grown.
Well, in 'Bilbo goes back in time' fanfiction, a possible plot is that Bilbo goes back to the time before Smaug took over the Lonely Mountain. He could then try to warn the dwarves and help them better prepare for the dragon's arrival. This might involve him teaching them new battle strategies or helping them find a better hiding place for their treasures. Another interesting idea is that Bilbo travels back to the time of the great elven kingdoms' prime. He could experience the height of elven culture and maybe even learn some ancient elven magic that he could bring back to his own time.
One interesting plot could be Natsu going back in time to prevent a great disaster that happened in the past of his world. For example, he might try to stop the initial attack of a powerful dark guild that had long - lasting negative impacts. Another plot could involve Natsu traveling back to his own childhood and having to deal with his past self, which could lead to some comical and heartwarming moments as he tries to impart some of his current wisdom.
One interesting plot could be Stiles going back in time and trying to prevent a major tragedy from happening in the past that has consequences in his present. For example, he might stop a villain from getting a powerful artifact that later causes chaos in his own time.
One interesting plot could be Hermione going back in time and preventing certain tragedies from the original story. For example, she might stop the death of a beloved character. Another could be her using her modern - day knowledge to change the course of wizarding history, like introducing new spells or concepts earlier.