Well, it could be something like a fire - based kekkei genkai that allows Naruto to control blue - flame fire which is hotter than normal fire. This would give him an edge in battles and also a new look to his fighting style.
It could be a water - based kekkei genkai. Since the Wave arc has a lot to do with water, it would make sense for Naruto to awaken a kekkei genkai related to water. This could give him an edge in battles, especially in the Wave region where water is abundant.
Having a kekkei genkai in fanfiction could completely transform Naruto's journey. It might unlock hidden potential within him, affect his relationships with other characters, and introduce new conflicts and resolutions that weren't present in the original storyline.
One common combination is the Sharingan and the Rasengan. The Sharingan's ability to analyze and predict movements can be really useful when Naruto is forming and launching a Rasengan. Another could be the Byakugan and Sage Mode. With the Byakugan's enhanced vision, he can better sense the chakra flow around him in Sage Mode, making his attacks more precise. Also, sometimes you see him with the Ice Release along with his regular Wind Release. He could then create ice - infused wind attacks that are both cold and sharp.
Another possibility in fanfics is that Naruto could have a Kekkei Genkai that is related to space - time manipulation. This could be inspired by his connection to the Nine - Tails and the fact that he has access to a lot of chakra. With this Kekkei Genkai, he could teleport short distances or even create small pocket dimensions to store items or trap enemies.
In some fanfictions, a side character from the original Naruto series could be made into the main character. For example, Rock Lee. He doesn't have any Kekkei Genkai in the original, but in this fanfiction, he could be given one of the 9 Kekkei Genkai and the story could be about how he overcomes the limitations he had before with his newfound power.
One interesting kekkei genkai in Naruto fanfiction could be the ability to control time on a small scale. This would allow a character to freeze an opponent briefly in battle or speed up their own movements. Another could be the power to manipulate elements in unique ways, like combining fire and water to create a scalding steam attack. And there's also the kekkei genkai of telepathy, which enables a character to read minds and communicate mentally with others, giving them an edge in both combat and strategic planning.
His relationship with Sasuke might become more competitive. If Naruto awakens a powerful kekkei genkai, Sasuke, who is always striving to be stronger, would see Naruto as an even greater rival. This could lead to more intense training sessions between them and also some tension in their friendship.
A great idea for Naruto Kekkei Genkai fanfiction would be to focus on a character who has a Kekkei Genkai that is considered a curse rather than a gift. They might be shunned by their village because of it. But as the story progresses, they learn to use it in a way that benefits everyone. For instance, a Kekkei Genkai that can absorb the life force of others could be used to heal instead. Another concept could be a Kekkei Genkai that gives the user the ability to communicate with animals in a very deep way, much more than normal ninja techniques. And then there's the idea of a character with a Kekkei Genkai that can transform into different elements, not just one like the normal transformation jutsu.
One possible kekkei genkai in Uzumaki Clan fanfiction could be an enhanced form of chakra control. Since the Uzumaki are known for their large chakra reserves, a fan - made kekkei genkai might be the ability to manipulate chakra in unique ways, like forming complex seals without using hands. This would give them an edge in battle as they could quickly cast powerful jutsu.