Well, in some fanfictions, Naruto might obtain all kekkei genkai through some sort of ancient and powerful jutsu. Maybe he discovers a hidden scroll or meets a mysterious sage who imparts this power to him.
In fanfiction, it could be due to some special training. Maybe he meets a super powerful mentor who has knowledge of all kekkei genkai and teaches him the secrets. Or perhaps he discovers some ancient jutsu that unlocks this ability within him.
Naruto himself is often a popular character in these fanfics. Since he has a unique ability to adapt and learn, fans might like to see how he would interact with all the kekkei genkai. Sasuke is also likely to be popular, as his natural talent and quest for power could be further explored in the context of different kekkei genkai.
One interesting concept could be the unique combinations of kekkei genkai. For example, the mixing of different elemental releases in ways not seen in the original Naruto series. It might also explore how characters with rare kekkei genkai interact with the existing Naruto world and its power structures.
One interesting kekkei genkai in Naruto fanfic could be the ability to control time on a small scale. For example, a character might be able to slow down time for a brief moment during a fight, giving them an edge. Another could be the power to manipulate light and shadow in unique ways, like creating illusions that are almost impossible to detect. And some fanfics might feature a kekkei genkai that allows a character to communicate with animals on a deeper level, similar to how Naruto can communicate with the toads.
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.
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.
Kekkei genkai can be a major driving force in the plot of Naruto fanfic. If a character has a unique kekkei genkai, it can make them a target. For example, if a character has the ability to control rare elements, other villages or villains might try to capture them to use their power. This can lead to a chase or a battle to protect the character. It can also change the power dynamics in a fight. A powerful kekkei genkai can turn the tide of a battle, creating unexpected twists.