Another plot might be that Harry goes back in time and gets involved in the lives of his parents. He could try to understand them better and in the process, change the way they view the world. This might lead to a different future where his family situation is much more stable and positive.
In some fanfictions, Harry goes back in time and decides to train himself better. He could seek out different magical knowledge or combat skills that he didn't have the first time around, which then changes his future interactions and battles. For example, he might learn ancient spells that give him an edge against Voldemort.
Well, in some fanfictions, Harry goes back in time to fix his relationships. He might go back to be a better friend to Ron and Hermione from the start. Also, he could use his knowledge of future magical items to gain an edge. Like, he could get his hands on some powerful spells or artifacts before Voldemort does. And sometimes, he goes back to change the Hogwarts curriculum, making it more practical and useful for the coming battles.
One interesting plot could be Harry going back in time to prevent the death of his parents. He might use his knowledge of future events to outwit Voldemort and his Death Eaters. Another plot could be Harry going back to his first year at Hogwarts and changing the way he interacted with certain characters like Snape, which could have a huge impact on the overall story. And he could also try to change the fate of some of the minor characters who died in the original story.
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 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.
One interesting plot could be Naruto Uchiha using his future knowledge to prevent the Uchiha massacre. He might try to change the minds of the village elders and stop the cycle of hatred before it spirals out of control.