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.
Well, in many fanfictions, Naruto often starts by facing a life - threatening situation. This intense moment somehow triggers a connection with the Kyuubi within him. Maybe it's during a battle against a really powerful enemy that he has no other choice but to tap into that power. It could also be due to some kind of emotional turmoil, like seeing his friends in great danger.
Well, in certain fanfic concepts, Naruto could control Kyuubi chakra with the help of unique jutsu or seals. For example, he might discover a new sealing technique that allows him to better manage the flow of the Kyuubi's power. This new seal could work in harmony with his own chakra system, enabling him to draw on the Kyuubi's strength without being overwhelmed. Also, some fanfictions might suggest that his strong emotional bonds, like his friendship with his comrades, give him the extra mental fortitude to control such a powerful chakra source.
The fanfic might center around the relationship between Naruto and the fem Kyuubi. Since she is the first chakra user, she could teach Naruto some ancient and powerful chakra techniques. This could lead to Naruto becoming even stronger and more respected in the ninja world. And of course, there could be a bit of a romantic sub - plot as they grow closer.
In some fanfictions, controlling the Kyuubi chakra might change Naruto's appearance. He could have some physical features related to the Kyuubi, like red - tinted eyes or a more ferocious look when using the chakra. Also, his relationships with others might be affected. Some might be in awe of his new power, while others could be afraid of him.
One interesting 'Naruto Kyuubi Chakra' fanfiction could be one where Naruto has better control over the Kyuubi's chakra from the start. It changes the whole dynamic of his early battles and how others perceive him in the village.
In fanfiction, the Kyuubi's Yin chakra in Naruto is often portrayed as a source of great power and mystery. Some fanfictions might show Naruto having to master this part of the chakra to gain new abilities, like enhanced control over illusions or a deeper connection to the spiritual side of his ninja powers.
Naruto would likely develop more control over his chakra with the help of the fem Kyuubi. He might become more mature in his approach to battles and life in general. The fem Kyuubi, on the other hand, could develop more human - like emotions as she spends time with Naruto.
In fanfiction, the 'Naruto Kyuubi Chakra' often plays a central role in power - ups. It can make Naruto much stronger than in the original story, allowing him to defeat powerful enemies more easily.
One role is to enhance Naruto's combat abilities. It can give him an edge in battles, like allowing for more unpredictable attacks. For example, it could make his shadow clones more versatile.