Perhaps the child has dreams about the Kyuubi's past. These dreams lead the child on a journey to uncover secrets about the Kyuubi that no one else knows. Along the way, they meet old allies and enemies of the Kyuubi. The child's journey also helps them to understand their own identity better, as they are a combination of Naruto and the Kyuubi.
The plot could involve the child being sought after by various ninja clans who want to use the power of the Kyuubi within the child for their own purposes. The child, with Naruto's teachings, resists and tries to find a way to use the power for the good of the village. Maybe the child discovers a new form of chakra control that combines Naruto's Uzumaki heritage and the Kyuubi's power.
One idea could be exploring the relationship between Naruto and the Kyuubi no Kitsune in a more spiritual way. Maybe Naruto can have dreams where he actually communes with the fox spirit and gains new insights about his powers. Another plot could involve a situation where the Kyuubi's powers start to merge with Naruto in unexpected ways, causing him to develop new abilities that he has to learn to control quickly.
One idea could be that the female Kyuubi has the ability to transform into a human form and she becomes Naruto's secret protector. She uses her powers subtly to keep him out of harm's way while he's on his missions, and Naruto starts to notice strange things happening but doesn't know it's her at first.
Maybe in the fanfic, Naruto gets injured while protecting the Fem Kyuubi from some other powerful force. This act of self - sacrifice makes her realize her deep love for him. Then, they start to train together, not just for power but also to strengthen their bond, sharing their secrets and fears during the process.
Well, in some fanfics, the Kyuubi's obsession might result in it influencing Naruto's chakra in a unique way. This could lead to Naruto developing new and unexpected jutsu. Also, the Kyuubi could be so obsessed that it tries to merge with Naruto in a different way than just lending its power, like actually becoming one entity with Naruto but still maintaining their individual consciousnesses to some extent.
One interesting plot idea could be exploring how Minato's relationship with the Kyuubi affects Naruto. For example, Naruto discovers some hidden memories of Minato's encounter with the Kyuubi that give him new powers or insights. Another idea is a story where Minato has to return from the afterlife briefly to help Naruto control the Kyuubi's power more effectively. Maybe there could also be a plot where the Kyuubi has a change of heart due to Naruto's kindness and decides to reveal secrets about Minato that no one else knew.
Well, in some 'naruto kyuubi child fanfic', the focus might be on how Naruto's life changes when he first realizes the presence of the Kyuubi within him as a child. Maybe he starts having strange dreams that are actually the Kyuubi's memories. Or perhaps he finds that he can draw on a small amount of the Kyuubi's power without fully transforming, which he uses to win a small local competition in the village. There could also be a story where the Kyuubi's chakra affects Naruto's growth, making him grow faster physically or mentally in some aspects as a child.
One idea could be exploring how the child of prophecy discovers their true power earlier than in the original Naruto story. Maybe they start to unlock unique jutsu that no one has ever seen before, which changes the course of the ninja world.
One idea could be exploring the bond between Naruto and the Kyuubi in a new way. For example, they could have a shared dream where they are in a strange, alternate world and have to work together to find a way back. Another plot could involve Naruto using the Kyuubi's power to save a village from a new, powerful enemy that no one else can defeat. And a third could be about the Kyuubi revealing a long - lost secret about Naruto's family that changes his perspective on his own powers.
One interesting idea could be the unique ways Naruto combines his skills with the power of the Kyuubi cloak. For example, he might develop new jutsu that are only possible when in the cloaked state. Another idea could be how the cloak affects his relationships with other characters. Some might be in awe of his new power, while others could be a bit fearful.
One idea could be a story where Naruto discovers a hidden power within the Kyuubi suit that allows him to time - travel. He could use this power to prevent certain tragedies in the Naruto universe. Another idea is that the Kyuubi suit starts to have a mind of its own and Naruto has to learn to cooperate with it in a new way, like sharing thoughts and strategies directly.