Well, it could be that Bella goes back in time and she has to blend in with the society Elijah is in. She has to learn the customs and ways of that time period. Along the way, she finds out that Elijah has a different personality than she expected. He might be more carefree or more burdened by his family's history. As she tries to get closer to him, she has to deal with other vampires who are jealous of her attention towards Elijah. And they might plot against her, which adds more drama to the story.
Another plot could be that Bella is sent back in time by some magical force related to Elijah. When she arrives, she finds Elijah in a difficult situation, like being trapped by an enemy. Using her wits and any powers she might have, she helps him escape. This starts a chain of events where they become allies and then, over time, more than that. They might travel through different historical events together, with Bella always having the knowledge of the future in the back of her mind to help them out.
She could change the whole dynamic of Elijah's life. For instance, if Elijah was on a path of revenge in his original timeline, Bella might be able to show him a different way. She could introduce him to new ideas and values that were not present in his time. This could lead to a completely different version of Elijah, one who is more open - minded and less consumed by his past grudges.
One possible plotline could be that Noctis goes back in time to prevent the fall of his kingdom. He could use his knowledge of the future to stop the events that led to its destruction. For example, he might prevent the betrayal of a key ally or stop the spread of a deadly plague that weakened the kingdom. Another plotline could be that Noctis goes back to a time when his father was still alive. He could then learn more about his father's rule and gain valuable advice on how to be a better king. Or perhaps he goes back in time to change a personal decision that had far - reaching consequences, like a choice he made about a relationship that affected his leadership later on.
Well, they could go back in time and end up interfering with their own past selves. This could create all sorts of chaos, like a time paradox. Maybe Naruto as he is in the present time meets his younger self and has to convince the younger Naruto to trust him. Or Sakura could use her medical skills to heal someone in the past who was important to their development. And Sasuke might use his new skills to take on enemies in the past that were too strong for them at that time.
Ruby could go back in time and end up in a different version of her world. In this new timeline, things are very different from what she knows. She has to adapt quickly and find a way to get back to her own time. Along the way, she meets alternate versions of her friends and foes. She might also discover that the reason she was sent back in time was part of a much larger plan by an unknown force. This could lead to a journey of self - discovery as she tries to understand her role in this grand scheme and how to use it to her advantage.
One possible plotline could be Anduin going back in time to prevent a great war. He might try to change the actions of key figures that led to the conflict in the first place. For example, he could go back and try to reason with Arthas before he fully embraced the Lich King's power. Another plotline could be Anduin going back to learn from the great heroes of the past. He could study under Uther the Lightbringer and gain new insights into the Light, which he could then bring back to his own time to help in the fight against the forces of darkness. And a third plotline could be that Anduin goes back in time accidentally and has to find a way to get back while also not disrupting the timeline too much.
One possible plotline could be Kakashi using his knowledge from the future to prevent Sakumo's suicide. He might try to change the events that led to Sakumo being shamed in the village. For example, he could expose the real reasons behind certain missions' failures that were wrongly blamed on Sakumo. This would not only save Sakumo but also potentially change the entire future of the Hidden Leaf village, as Kakashi's own life and development were deeply affected by Sakumo's death.
One possible plotline could be that Luke and Leia go back in time to prevent the rise of the Empire. They might try to stop key events like the corruption of Anakin Skywalker. For example, they could warn the Jedi Council about Palpatine's true nature. Another plotline could be that they go back to save their mother. They would have to figure out how to do this without changing too much of the future. Maybe they'd work with young Obi - Wan Kenobi.
One possible plotline could be Naruto using his old and experienced self to prevent past tragedies. For example, he might stop the Uchiha massacre. He could use his knowledge of jutsu and his understanding of people to change the course of history and bring about a more peaceful future from the start.
One possible plotline could be Naruto using his newfound time - traveling ability to prevent some of the major tragedies in the past. For example, he might try to stop the Uchiha massacre. He could also use his knowledge from the future to help his younger self become stronger faster, perhaps by teaching him some advanced jutsu he learned later in life.