The outcome of the fight in the 'naruto fights the kyubi fanfiction' is quite uncertain. Naruto has his own set of skills, like his Rasengan and his ability to use shadow clones effectively. On the other hand, the Kyubi has raw power that is almost unrivaled. If Naruto is able to find a weakness in the Kyubi, perhaps something related to its past or its connection to the ninja world, he could win. But if the Kyubi manages to break Naruto's spirit, then the Kyubi would be the victor.
In this kind of fanfiction, Naruto might face a great challenge. He could use his new jutsu that he has learned over time to combat the Kyubi's powerful attacks. Maybe he'd have to tap into some hidden reserves of his chakra.
One great Naruto fanfic about him controlling Kyubi power is often centered around his growth as a ninja. It shows how he overcomes the initial struggle of harnessing such a powerful force within him. As he gradually gains more control, his abilities in combat and his standing in the ninja world improve significantly.
Another theme is acceptance. Naruto has to accept the female Kyuubi as she is, with her own personality and motives. And the female Kyuubi has to accept Naruto's way of life and his values. This mutual acceptance is often a key part of the story. For instance, in some fanfictions, the female Kyuubi initially doesn't understand Naruto's desire to protect the village, but gradually comes to accept it.
One consequence could be that he becomes extremely powerful. His physical abilities like strength, speed, and endurance are enhanced. He can also use more powerful jutsus with the extra chakra boost from the Kyuubi.
One interesting way is when Naruto absorbs chakra through his shadow clones. In some fanfictions, the clones can be used not just to gather information or attack, but also to absorb the chakra of the opponents they interact with. Then, they transfer this absorbed chakra back to Naruto, making him more powerful.
Perhaps there is an ancient artifact or a powerful curse that causes Naruto to absorb all chakra. In the fanfiction world, it's common to introduce such unique elements. For example, he might find a magical scroll that, when opened, starts sucking in all the chakra in the vicinity and then channels it into Naruto. Or it could be a curse placed on him by an enemy, but instead of harming him, it gives him this strange power to absorb all chakra.
The consequence might also be a shift in the balance of power in the Naruto universe. With all that chakra, Naruto could potentially change the political situation. He could end wars single - handedly or force the different ninja villages to re - evaluate their strategies. Moreover, his own physical and mental state might be affected. There could be a struggle within him to keep his identity intact while dealing with such an overwhelming power source.
He could share it with Hinata. Given their relationship, Naruto might transfer some of his chakra to Hinata to protect her during a dangerous situation. This would also strengthen their bond further in the fanfiction.
You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own. Use the search function and type in 'Naruto' and 'Kyubi' to find relevant stories.