One way is through enhanced emotional bonds. If Naruto experiences a very strong emotion like extreme love or a sense of justice, it might trigger a stronger connection to the Kyuubi and thus more power. Another way could be through new types of seals. Maybe a fanfic writer creates a seal that not only contains the Kyuubi but also channels its power more effectively to Naruto.
There are several ways Naruto can get power from the Kyuubi in fanfic. He could be in a situation where he has to merge his consciousness with the Kyuubi's on a deeper level. This could result in a power boost as they become more like one entity. Additionally, if there are other characters in the fanfic who have knowledge about the Kyuubi that Naruto doesn't, they could teach him new methods to draw power from it. For example, an ancient sage in the fanfic might know a secret technique to access the Kyuubi's most powerful form of chakra that Naruto can then learn and use.
Well, often in Naruto fanfic, Naruto can get power from the Kyuubi when he manages to break through the mental barriers that were set in the original series. He might be able to communicate better with the Kyuubi and convince it to lend him more power. It could also be that some external force or event in the fanfic world allows him to access the Kyuubi's power in a new way, like a magical artifact or a new type of jutsu.
One common way is by sharing its chakra. Naruto can draw on this extra chakra to increase his strength and speed. Another way is through its knowledge. Kyuubi has a long memory and can pass on useful information about the ninja world.
In some fanfiction concepts, it might be due to a unique chakra interaction. Maybe the Kyuubi's powerful and ancient chakra somehow triggers a latent ability within Naruto that results in the manifestation of the Rinnegan. It could also be part of some kind of prophecy or destiny within the fan - created world of the story.
In certain fanfictions, Naruto's lightning power is used in a more strategic way. He might use it to create diversions. For example, he could make a bright flash of lightning in one area to distract his opponents while he moves to a different position for a surprise attack. He could also use it in combination with his shadow clone jutsu. The clones could be made to carry a small amount of lightning power each, and when they are attacked or dissipated, they release a shock that stuns the enemy.
Often, in fanfic, Naruto gets stronger by delving deeper into his Uzumaki heritage. Since the Uzumaki clan was known for their large chakra reserves, he could learn to fully tap into this potential. This might involve special training techniques passed down within the clan that were previously lost or forgotten.
One way is through Naruto's appearance. The Kyuubi's power might make Naruto's hair look wilder, like the Kyuubi's fur. His face could also get some markings similar to the Kyuubi. Another way is his strength. When Naruto uses the Kyuubi's power, he might be so strong that it scares people and they start to see him as a demon. Also, the Kyuubi's negative emotions can influence Naruto, making him seem cold and cruel at times.
In some fanfics, when in Kyuubi form, Naruto can be more aggressive. The Kyuubi's influence might make him less hesitant in battle and more direct in his attacks.
One common way is through power boosts. The Kyuubi's chakra gives Naruto the strength to take on tougher opponents.
Naruto might learn about the balance between good and evil from Kyuubi. The Kyuubi has a wild and often considered 'evil' nature, but through their connection, Naruto can understand that even within that so - called 'evil' there are aspects that can be used for good. For example, the raw power of the Kyuubi can be harnessed for protection rather than destruction. Additionally, Naruto can learn from Kyuubi's long - held grudges and how to let go of negative emotions, as Naruto tries to help the Kyuubi move past its own anger and hatred towards humans.
Regular Naruto fanfic often focuses on Naruto's relationships with his friends and his growth within the village. But 'unsocial Naruto fanfic' is different. It can focus on Naruto being alone, like when he's dealing with inner demons that he doesn't want to share with others. It shows a side of Naruto that we don't often see in the main story.