Naruto is often a common character. Since Naruto has a strong bond with Kakashi, he might be involved in Kakashi's time - traveling adventures. Sasuke could also be there. Their relationship with Kakashi in the original story makes it likely for them to show up. And of course, Guy would be a great addition. His friendly rivalry with Kakashi would add some humor and action to the time - travel scenarios.
I think Rin would be an interesting character to pair with Kakashi in time travel fanfictions. Since she was an important part of Kakashi's past, their relationship could be explored further. Maybe Kakashi travels back to save her from her tragic fate, and they end up having a different kind of relationship as a result.
Often, Naruto is paired with Kakashi in such fanfictions. Their bond from the original series can be explored in new ways in the context of Kakashi's reincarnation. For example, Naruto might be the one to discover Kakashi's reincarnated form and help him adjust.
Danzo could also be a common antagonist. He was very power - hungry and had his own dark secrets. In a time - travel scenario, he might view Kakashi and Naruto as threats to his control over the Hidden Leaf Village in the past. He could try to eliminate them to maintain his grip on power.
Obviously, Kakashi is one of the main characters since it's about his time travel. Minato is also a central figure as he is part of Team Minato that Kakashi travels back to be with. And of course, the other members of Team Minato like Obito and Rin are likely to be important characters as well.
In a Sakura and Kakashi time travel fanfiction, they could end up in the past during a major war. Kakashi would be a great asset with his Sharingan and combat skills. Sakura, on the other hand, could help the wounded soldiers. Their presence in the past could change the outcome of the war. For example, they might be able to save some important characters who were supposed to die. This would then lead to a completely different future when they return to their own time.
One common theme is redemption. Since they go back in time, both Obito and Kakashi often try to atone for their past mistakes. For example, Obito might try to prevent the events that led him to become evil in the first place.
One common theme is redemption. Since Kakashi can go back in time, he often tries to make up for past mistakes or prevent tragedies that occurred in the original timeline. For example, he might try to save a character who died before. Another theme is the changing of fates. He can change the destiny of not only himself but also of his friends and the whole village. He can use his knowledge of future events to better prepare for threats.
One common theme is redemption. Since Kakashi has a lot of regrets in his life, in time - travel fanfics, he often tries to make up for his past mistakes. For example, he might try to save his comrades who died in the original timeline.
One common theme is self - discovery. As they travel through time, both Naruko and Kakashi often learn more about themselves, their strengths, and their weaknesses. For example, Naruko might realize she was more capable in the past than she thought she was.
Another theme is the exploration of relationships. Since Kakashi and Minato have a complex relationship in the original story, in time travel fanfictions, they can have new interactions. They might be able to understand each other better, like Minato getting to see Kakashi as a more mature and capable person if he travels to the future, or Kakashi seeing Minato's leadership in a new light if he goes back in time.