The Kyuubi has been with Naruto since his birth, sealed inside him. Fanfiction writers like to play with this idea of co - existence. Naruto's journey of becoming a great ninja while carrying the Kyuubi's power makes it logical for the Kyuubi to be protective. As Naruto faces many challenges and enemies, the Kyuubi, being a powerful entity, can step in to protect him. Also, over time, as Naruto grows and shows his strength of character, the Kyuubi may come to respect and protect him more. This adds an interesting dynamic to the fanfiction stories.
The fem Kyuubi could also be protective in a more subtle way. Maybe she gives Naruto advice based on her long - time existence and knowledge. Like warning him about certain dangerous jutsus or shinobi he should avoid. She uses her wisdom to keep Naruto out of harm's way.
One way could be through mental support. In certain fanfictions, the Kyuubi might communicate with Naruto in his mind during tough situations. It could give him advice or just boost his confidence, like saying 'Don't worry, brat. I won't let anything bad happen to you.' This is a form of protection as it helps Naruto face difficulties more bravely.
One popular fanfiction could be 'Kyuubi's Vow'. In this, the Kyuubi forms a deep bond with Naruto early on and is extremely protective. It shows the Kyuubi using its power to shield Naruto from various threats that come his way during his early days at the ninja academy. Another one might be 'Kyuubi's Guardian'. Here, the Kyuubi not only protects Naruto physically but also guides him in understanding his own powers and the world of shinobi better.
One interesting plot point could be how the other characters in the Naruto world react to the fem Kyuubi's protectiveness. Some might be suspicious, while others might see it as a positive change. For instance, Kakashi might be initially cautious but then come to realize that it benefits Naruto's growth.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can easily search for 'Naruto x Kyuubi yaoi' in its search bar. There are filters available too, which can help you narrow down your search to the most relevant stories.
One popular 'Naruto x Kyuubi yaoi fanfiction' story could be 'Bond of Spirits'. It explores a deep emotional connection between Naruto and Kyuubi. In this fic, their relationship evolves from Naruto initially fearing Kyuubi to gradually understanding and forming a unique bond that has elements of a yaoi - like relationship, with a lot of emotional exchanges and character development.
The idea of Kyuubi being protective can also lead to new relationships being explored in fanfiction. Naruto might have a different kind of bond with the Kyuubi, not just as a host - parasite relationship but more like a partnership. This can then affect how he interacts with other characters. In terms of plot, it could lead to story arcs where the Kyuubi's protection is tested, like when a super - powerful villain tries to find a way to bypass the Kyuubi's protection to get to Naruto.
Well, it might be that in the fanfiction, Naruto goes to the frozen waterfall to have a conversation with Kyuubi. They could be discussing Naruto's growth as a ninja and how Kyuubi's power can be better harnessed. The frozen waterfall setting adds a sense of isolation and mystery to the encounter.
Well, one reason could be that the author wants to explore an alternate universe. Maybe in this fanfiction's version of the Naruto world, the events leading to the sealing of the Kyuubi never occurred. It could be due to different political situations among the ninja villages, or perhaps a different chain of events that prevented the Kyuubi's attack on Konoha in the first place. So, without the attack, there was no need for the seal.