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 fanfic, a typical way Kyuubi helps Naruto is during battles. It can give Naruto an edge by enhancing his physical abilities. Also, Kyuubi can sometimes communicate with Naruto and offer advice on how to deal with difficult opponents or situations. This communication can be a crucial factor in Naruto's development in the fanfic.
One possible reason could be the loss of a dear friend. Naruto values his friends deeply, and if he were to lose one, it would break his heart. For example, if Sasuke were to die or turn against him completely in a way that Naruto couldn't fix, it would be a huge blow.
Well, the Kyuubi might use its chakra to soothe Naruto's emotional pain. It could send warm waves of its powerful chakra through Naruto's body, making him feel more at ease and less heartbroken.
She uses her knowledge of magic. For instance, if the trial involves a magical crime, she can explain complex magical concepts to the court. This helps in determining the nature of the crime and whether it was intentional or accidental. She also has a great memory, so she can recall past cases or events that are similar, which can be used as references in the current trial.
One interesting plot could be Naruto using his unique bond with Kyuubi to help it regain its lost memories. Naruto might explore the Kyuubi's past and discover things that even the Kyuubi itself had forgotten. This could lead to new powers or a deeper understanding between them.
One way Ino helps is by being a source of emotional support. Her friendship with characters like Sakura can be a stabilizing force. In some fanfictions, she might offer advice on relationships or personal growth.
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.
Isolation is also a theme. Because of the Kyuubi, Naruto is often ostracized by the villagers when he's young. Fanfics might focus on how he copes with this isolation, whether it's by finding solace in his own training or by forging unlikely friendships despite the villagers' attitudes. This theme adds depth to the character of Naruto in the context of the young kyuubi situation.
One way Marge can help is by being a plot device. Her presence can force the wizard characters to be more cautious about using magic, which adds tension to the story. For instance, if they are in a situation where Marge is nearby, they have to hold back their magical abilities, and this can lead to some interesting and suspenseful scenarios.
One common theme is the power of love to overcome differences. Since Naruto is a human ninja and the female Kyuubi is a powerful, other - worldly being, their love has to bridge this gap. Another theme is redemption. The female Kyuubi might have a past full of chaos and destruction, but through Naruto's love, she could find a new path.
Often, there might be a focus on the relationship between the childish female character and Naruto himself. Since Naruto has a connection to the Kyuubi, their interactions could be a central part. For example, the female character might be in awe of Naruto's power related to the Kyuubi or vice versa. Also, the fanfic might explore how the female character's childish nature affects her relationship with the Kyuubi's power, like she could be naively curious about it or use it in unexpected ways.