She might become more empathetic. Meeting people from the past, especially those who were suffering or in difficult situations, could make Serena more understanding. She could see the world from a different perspective and this would change how she interacts with others in her own time. For example, if she sees how people in the past fought for equality, she may be more involved in similar causes in her present.
Noctis' character could develop a greater sense of responsibility. Since he has seen the consequences of his actions in the future, he would be more cautious and calculated in his decisions when he goes back in time. He might also become more self - reliant as he realizes he can't always rely on the same people or circumstances. For example, if he lost someone important in the future due to his actions, he would be more independent in his choices to prevent that loss again.
He would likely become more cautious. After experiencing such tragedies in his first 'life', he would think twice before making hasty decisions. This could make him a more calculating and less impulsive leader.
She could become more independent. In 1918, she would be in a strange time without her usual support system. This would force her to rely on herself more, making her stronger.
She might become more confident in her earlier years. In the original story, Arya faced many hardships that made her grow in a certain way. But if she goes back in time, having the knowledge of future events, she could be bolder in her actions and decisions from a young age. For example, she might be more assertive in dealing with Sansa when they were kids, and not let Sansa's girly ways get to her as much.
In this fanfic scenario, Anakin's character would develop with a greater sense of purpose. He would no longer be a victim of fate. He could take control of his destiny. He would be more self - assured, knowing what lies ahead. His relationships with other characters would also be different. He would be more of a leader, guiding others based on his future knowledge. This would transform him into a more positive and influential figure in the Star Wars universe.
One possible plot could be Serena going back in time to prevent a major disaster in her world. For example, she might go back to stop an evil force from being released. In the past, she could meet younger versions of her friends and family, and they might not recognize her at first. She would have to use her knowledge from the future to try and change things for the better.
Going back in time gives Severus the opportunity to develop a different relationship with power. In the original timeline, his pursuit of power through the Dark Arts and association with Voldemort led to many problems. But if he goes back, he could use his knowledge to gain power in a more positive way. He could become a powerful force for good in the wizarding world, using his intelligence and skills to promote peace and cooperation. His character would then be seen as a reformed and wiser version of himself, rather than the conflicted and often tragic figure he was in the original story.
Kylo Ren's character could develop in a more positive way. If he goes back in time, he might see the mistakes of the past and decide to be a better person. For example, he could see how the Sith's ways led to destruction and choose the path of the Jedi instead.
In this fanfiction, Deku's character development could be quite complex. Going back in time, he may initially be overconfident because he thinks he knows what's going to happen. But as he realizes that changing the past has unforeseen consequences, he becomes more cautious. He also might develop a deeper understanding of his friends and their potential, as he gets to see them at an earlier stage. He could start mentoring some of them, which would in turn make him more responsible and mature as a character.
Sansa would be more assertive in her political moves. She has seen the consequences of inaction and bad decisions in the future. So, she would be quicker to make decisions that benefit her family and herself. For example, she might be more involved in military strategies to protect the North.