In some fanfiction ideas, when Vegito goes back in time, his power could be affected by the different energy levels in the past. Maybe the ki in the past is purer, which could either enhance his power further or require him to adapt in a new way. Also, if he has to hide his true power to not disrupt the timeline too much, he might have to find new ways to use his skills subtly.
When GT Goku goes back in time in fanfiction, his character may change in many ways. He could be more of a planner, thinking ahead about how to avoid the mistakes of his original timeline. He might also be more protective of his friends and family, knowing what they had to endure in the future. His sense of responsibility would likely grow, as he now has the power to shape the past and create a better future. This could lead to him being more involved in the political and social aspects of the Saiyan and Earth communities, rather than just focusing on his own training and battles.
His sense of responsibility would grow even more. Knowing the future, he would feel an even greater obligation to protect everyone. He might be constantly on guard and take on a more leadership role among the Z - fighters, guiding them in their training and battle strategies. He would also probably be more patient with the younger versions of his friends and family, understanding their potential better.
He might change the course of some major battles. For example, he could prevent the destruction of certain planets that were destroyed in the original timeline.
His power level would be off the charts compared to most past characters. Ultra Instinct Goku is extremely powerful, and in the past, there were few characters who could match him. Even someone like Vegeta in his earlier days would be no match for Ultra Instinct Goku.
His character could become more humble. Going back in time and seeing the past versions of people and events might make him realize how much he has changed over the years. He may also become more cautious. Knowing the consequences of certain actions from his original timeline, he'll be more careful with his decisions in the past. For example, he might think twice before revealing his identity as Iron Man too soon.
Link's relationship with his own past self could be a really interesting aspect. If he meets his younger self, there could be a sense of mentoring or even confusion. His younger self might not understand what's going on at first. And when it comes to friends like the Koroks, if he goes back to a time when the Korok Forest was in a different state, their interactions would be new and different. The overall web of relationships would be completely reshaped as he steps into a different time period in Hyrule's history.
If Killua goes back in time, his relationship with Gon could become stronger. He might use his knowledge of their future together to avoid any misunderstandings that happened before. For example, he could be more open about his feelings and fears earlier, which would deepen their bond.
Since Naruto has more knowledge of the future, Kakashi might start to rely on him more, which could shift their relationship. Naruto could also see a different side of Kakashi from the past, and this new understanding could deepen their connection. For example, they might have to face some challenges together that make them trust each other more than before.
His confidence would skyrocket. Naruto has always been confident, but with Madara's power, he'd have a new level of self - assurance. He'd know he could handle almost any threat. His sense of responsibility would also grow. Since he has such great power now, he'd feel an even greater obligation to protect his village and friends.
He may become more aggressive. The power of the nine - tails can influence his normal calm and determined self, making him more likely to act on impulse and attack first without thinking too much about the consequences.