One possible plot could be that the Kyuubi's chakra constantly overwhelms Naruto's mind, leading him to make rash decisions in battles. For example, he might attack his allies by mistake when the insanity takes over.
Well, for one thing, it allows for a fresh take on the Naruto universe. The insane aspect of Naruto can lead to different plotlines compared to the traditional Naruto stories. And the Fem Kyuubi adds an extra layer of intrigue as she has her own set of powers and personality traits. Their relationship can be explored in ways that are not possible in the original series, like how they might interact during battles or how they come to understand each other on a deeper level. It gives writers a chance to be really creative and come up with new story arcs and character developments.
It shows Naruto's vulnerability. Usually, he is seen as strong - willed, but in this fanfiction, the Kyuubi's influence exposes his weakness when it comes to his mental state.
One element that makes it funny and insane is when the author takes a normal Naruto concept and blows it way out of proportion. For instance, if the concept of chakra is turned into something like 'chakra candy' that ninjas have to eat to gain power. And when the fanfiction has a lot of physical comedy, like Naruto constantly tripping over his own feet while trying to perform a super - important jutsu. Also, when there are crossovers with really unexpected universes, like Naruto meeting the characters from a Looney Tunes world. This creates a really wacky and fun dynamic.
The insane godlike Naruto can completely transform the story. His enhanced powers mean he can take on greater challenges. For instance, he might be able to face off against stronger villains without hesitation. In relation to the Fem Kyuubi, he could have a more confident approach in their interactions. He's not the meek Naruto from the start of the original series. This new Naruto can also change the pacing of the story. Since he's more powerful, events might unfold more quickly as he's able to make bolder moves.
The key elements often include a reimagined Naruto with 'insane godlike' abilities. This could lead to a more dominant role for Naruto in his relationship with the Fem Kyuubi. Their relationship itself is a major element. It might not be a typical friendship or partnership but something more complex, perhaps with elements of mutual respect and dependence. The fanfiction may also explore how the Fem Kyuubi's nature affects the story. As a nine - tailed fox, she has a lot of power and a certain wildness. In this fanfiction, that could be both a source of conflict and a strength when combined with Naruto's abilities.
Another option is to ask in Naruto - related fan groups on social media platforms. People in these groups are often very passionate about Naruto and may be able to point you to some good insane Naruto x Fem Kyuubi fanfictions.
Naruto, with his mental insanity, would likely develop in a very erratic way. His actions might be unpredictable as he tries to come to terms with his own mind and the presence of the Fem Kyuubi. The Fem Kyuubi, on the other hand, could start off as a more stable entity but gradually be influenced by Naruto's insanity. Maybe she becomes more empathetic towards his situation.
One possible plot twist could be that Naruto's mental instability causes him to misinterpret the Fem Kyuubi's intentions. Maybe he sees her as a threat when she's actually trying to help him. This could lead to a lot of internal conflict within Naruto and also create tension in their relationship.
A good Naruto and Kyuubi fanfiction often has a deep exploration of their relationship. For example, it could show how Naruto overcomes the initial fear of the Kyuubi's power and instead learns to work with it. It should also stay true to the characters' personalities from the original series. If Naruto acts completely out of character, it won't be as appealing.