Definitely Sasuke. Their relationship has always been complex and full of unspoken feelings. Naruto is also a strong contender as he has always cared for Sakura deeply. Rock Lee might be in the harem too. His admiration for Sakura has been quite obvious throughout the series. And perhaps Kiba, who could see Sakura in a new light during the time - travel events. Also, an older or more experienced version of a minor character from a different clan might be attracted to Sakura's growing power.
One plot idea could be that Naruto time - travels back to the early days in the village. Sakura, being the center of a harem, has different ninja from different clans vying for her attention. Naruto, with his knowledge of the future, tries to navigate this new dynamic while also protecting Sakura from potential threats within the harem. Another could be that Sakura herself time - travels and has to deal with a harem that forms around her in the past, where she has to balance her own goals and the feelings of those in her harem.
A different plot could involve Naruto traveling back and finding that Sakura has a completely different personality in this harem - set - up. She could be more confident and forward, which catches Naruto off - guard. He then has to adapt to this new Sakura while also exploring his relationships with the other members of the harem. This could lead to some comical and also some very heart - felt moments as he discovers new sides of his friends and potentially falls in love in a whole new way.
The relationships would develop very differently. Naruto's time travel gives him an advantage in understanding the characters better. He can anticipate Sakura's needs and wants before she even realizes them. This would make their relationship more intimate faster. For the other characters in the harem, they would all be vying for Naruto's attention in different ways. Some might use their skills as ninjas to impress him, while others might rely on their emotional connection. Sakura, on the other hand, might have to step up her game and show Naruto that she is the best choice among the harem. This would lead to a more dynamic and interesting set of relationships compared to the original Naruto storyline.
One great Sasuke, Naruto, and Sakura time travel fanfiction is 'Time - Twisted Bonds'. In this story, they are sent back to their childhood days with their present - day knowledge. It's really interesting to see how they interact with their younger selves and try to change things for the better. Another good one is 'Journey Through Time' where they travel to different points in the Naruto timeline and face challenges that were not part of the original story.
There's also 'A Time - Traveling Trio'. This fanfiction focuses on how Naruto, Sasuke and Sakura's relationships change during their time - traveling adventure. They go back to key moments in their past and their interactions with each other and other characters are really well - written. It shows a different side of their friendship and rivalry as they work together to get back to their own time.
There's 'Time - Twisted Destiny' too. In this fanfiction, when Naruto and Sakura travel back in time, they find themselves in a situation where they have to be very careful not to disrupt the timeline too much. Their interactions with younger versions of their friends are really fun to read. The story also delves deep into Sakura's growth as she tries to use her medical skills in a more impactful way in the past.
Of course, some original Uchiha characters like Mikoto Uchiha. She was Itachi and Sasuke's mother. In a time - travel fanfiction, Naruto could interact with her in a way that changes the course of history. Maybe he saves her life, and she feels indebted to him, leading to her being part of his harem. Her motherly instincts could also be a factor in how she interacts with Naruto and the other members of the harem.
Naruto, of course. Since they are in the same team in the original story, it's very likely that Sakura will interact with Naruto. She might try to change his fate or help him in a different way. Sasuke is also a main character she'll interact with. Maybe she'll try to prevent Sasuke from going down his dark path. And Kakashi, as their teacher, will also be involved in their interactions.
There's also 'Back to the Beginning: Sakura's Time Travel'. In this fanfiction, Sakura goes back to the time when Naruto was still an outcast in the village. She decides to befriend him earlier and change the way the villagers see him. It has a lot of heart - warming moments as well as some great action scenes.