In some fanfiction, the Avengers could go back in time to change a small event that had a huge butterfly effect on the future. For instance, they might go back to when Loki first arrived on Earth and try to make him an ally instead of an enemy. This would require them to convince Loki, who is very distrustful, and also deal with the potential consequences of altering his path in the timeline.
One possible plotline could be that Harry and Severus go back in time to prevent certain tragedies from happening in the wizarding world. For example, they might try to stop Voldemort's rise to power much earlier. Another could be that they go back to change their own relationship. Maybe in the original timeline they were enemies, but now they have a chance to become allies or even friends.
Well, a cool plotline might involve the main character introducing modern ideas to the Marauders' time. Maybe they bring new spells or ways of thinking that completely change the dynamic at Hogwarts. It could be really exciting to see how the Marauders and their friends react to these new concepts.
They might go back in time and accidentally change something that has a huge ripple effect on the future. So then they have to scramble to fix it before they return to their own time. They could also go back in time to learn some long - lost magic from an ancient wizard or witch and bring that knowledge back to their time to defeat a new dark force.
One interesting plotline could be a civilian who is caught in the middle of a battle and is saved by the Avengers in a very unexpected way, like being teleported to safety by Doctor Strange at the last second.
One interesting plotline could be Wolverine having to team up with the Avengers to stop a powerful mutant - created virus that threatens to wipe out both mutants and non - mutants alike. He brings his unique combat skills and healing factor to the table, while the Avengers contribute their various superpowers and high - tech resources.
One interesting plotline could be the return of a long - lost Avenger who has been in hiding or captivity. For example, they might come back with new powers or a different perspective, causing a shift in the team dynamics.
Another plotline might involve Loki getting caught in a time - loop within an Avengers - related adventure. He keeps reliving the same day, and each time he has to interact with the Avengers in different ways to try and break the loop. This could lead to some really comical and also tense situations as he tries to figure out what's going on while the Avengers are getting increasingly suspicious of his behavior.
In this type of fanfiction, a great plotline could be Sansa influencing the political landscape much earlier. She could use her knowledge of how certain houses would act in the future to her advantage. For example, she could form early alliances with houses that she knows will be important later. She might also try to change the way her family views certain people. Maybe she could convince her father to see Littlefinger's true nature much sooner. This would not only protect her family but also change the entire power dynamic in Westeros.
One interesting plotline could be Castiel going back in time to prevent a major disaster in the past that has far - reaching consequences for the present. For example, he might stop a powerful demon from making a deal that would later lead to the death of many hunters.
In some 'Vegeta goes back in time' fanfictions, Vegeta might go back to the time when the Saiyans were still under the rule of King Vegeta. He could try to change the Saiyan culture from being so war - like and brutal. He might introduce new ways of thinking and training that would not only make the Saiyans stronger but also more united. This could lead to a completely different future for the Saiyans, where they don't get wiped out by Frieza and instead become a more dominant force in the universe. He could also form different alliances with other races much earlier, which would change the power dynamics in the galaxy.