He might be shocked. In the fanfic, if he sees things like his friends' future achievements or the new threats that emerge, it would surely startle him. For example, if he discovers that one of his friends has a family of their own and has become a great leader in the village, he would be proud but also a bit surprised at how much has changed.
With his usual determination. Naruto has always been one to face difficulties head - on. So, even if he's shocked by what he sees in the fanfic's future, he'll likely try to find solutions immediately.
I think Hinata could be an ally. She has always been in love with Naruto and would not stand by while he is in danger from Dark Naruto. Additionally, Shikamaru is smart and strategic. He might see the threat of Dark Naruto to the village and decide to assist Naruto, using his intelligence to come up with battle plans.
Well, sometimes in 'naruto vs dark naruto fanfiction', a cool plotline is when Dark Naruto has some new powers that Naruto has to figure out how to counter. For example, Dark Naruto might be able to control shadows in a way that Naruto has never seen before. Or perhaps Dark Naruto has allied himself with a powerful dark force from outside the ninja world. Naruto then has to not only battle his dark self but also this new threat.
In fanfiction, the Rinnegan is often depicted as more powerful than the Sharingan in many ways. The Rinnegan has abilities like the Six Paths techniques which can be extremely overpowered. For example, it can allow the user to control gravity, summon large creatures, and even revive the dead. While the Sharingan has its own set of cool abilities like predicting movements and casting genjutsu, it seems limited in comparison when it comes to the grand scale of power shown by the Rinnegan in most fanfictions.
In a fanfiction, the aliens could capture Naruto and try to study his unique abilities. The monsters then decide to rescue him because they realize his powers could be the key to defeating the aliens once and for all. The story could involve a lot of action as the monsters infiltrate the alien base to save Naruto.
In a fanfic, Naruto might power up by having a spiritual awakening. He could connect with the spirits of past Hokages in a deeper way, gaining their knowledge and some of their power. This could enhance his existing jutsu and give him new abilities. Vegeta could power up if he were to face a near - death experience against Naruto. This could trigger a hidden potential within him, like a new type of Super Saiyan form that has unique abilities. He could also fuse with another Saiyan (if there were another Saiyan available in the fanfic's scenario) to create an even more powerful being.
One common theme is self - improvement. Both Sakura and Naruto are constantly striving to get better in these fanfics. For example, Sakura might be trying to improve her combat skills to be on par with Naruto. Another theme is friendship. Despite their rivalry, their underlying friendship is often explored. It shows that they can compete and still care for each other.
In Gohan vs Naruto fanfics, a really cool plot is when their powers get combined somehow. For example, due to a magical or scientific accident, Gohan's ki and Naruto's chakra merge, creating a new and powerful force. Another interesting plot is when they have to fight in a world that has rules that are different from both of their own. This forces them to adapt in unique ways. Also, a plot where they are both de - powered and have to rely on their wits and basic fighting skills to compete can be very engaging.
In a Gohan vs Naruto fanfic battle, I think Gohan would win. His Saiyan heritage gives him a natural advantage in terms of raw power. He can fly and has energy blasts that could overpower Naruto. Naruto is strong, but his powers are more about ninjutsu and chakra control. Gohan's Super Saiyan forms would be too much for Naruto to handle.