One interesting plot point could be how Naruto's use of Shiki Fuujin affects his relationships with his friends. Since it's such a powerful and dangerous jutsu, they might be worried about him using it.
Perhaps in the fanfic, Naruto uses Shiki Fuujin in a creative way to defeat an otherwise unbeatable enemy. For example, he might sacrifice a small part of his own chakra instead of his life to perform a weakened but still effective version of the jutsu.
The villain in the fanfic could also be considered a main character. If Naruto is using Shiki Fuujin, it's probably against a powerful enemy. This enemy's motives and power level would play a crucial role in the story and how Naruto decides to use the jutsu.
In 'naruto uses shiki fujin fanfic', the story might focus on the consequences of Naruto using this powerful jutsu. It could explore how it affects his relationships with other characters. Since Shiki Fujin is a very dangerous and self - sacrificing jutsu, the fanfic could show how Naruto copes with the risks involved.
One interesting plot point could be Shiki's internal struggle. He has his own moral code which might conflict with the cut - throat nature of the Grail War. Another could be his relationship with his Servant. If he summons a Servant with a strong personality, there would be clashes and also moments of mutual understanding. For example, if he summons a heroic - type Servant who values honor, and Shiki has his own way of doing things.
Well, one place to look could be on fanfiction.net. There are often a variety of Naruto - themed fanfics there, and you might be able to find some that involve Naruto using Shiki Fujin. Another option is Archive of Our Own (AO3). It has a large collection of fan - created works as well.
One idea could be that Naruto discovers a hidden Uchiha ancestor in his family tree. This could lead to the dormant Sharingan gene awakening in him. He then has to learn to control the Sharingan while still maintaining his own unique ninja abilities. Another plot could be that during a battle with a powerful enemy, Naruto is somehow merged with an Uchiha ninja, and as a result, he gains access to the Sharingan. He then uses it to gain new insights into his opponents' moves and strategies.
Well, one interesting plot point could be how the main character, who might be in the shadows, interacts with the known Naruto characters in unexpected ways. For example, they could be secretly influencing the major events in the Naruto world without others realizing it.
Another plot point might be Lucoa sharing her dragon - related knowledge with the ninja. This could lead to new jutsu being created or new ways of thinking about power in the Naruto universe. For example, she might teach about dragon - like breathing techniques that could be incorporated into ninja training.
A really interesting plot point in 'Naruto' drunk fanfic is the exploration of the character's emotions. When drunk, Naruto might show his insecurities more openly. He could start talking about his feelings towards Sasuke in a more raw and unfiltered way. This can create some really emotional and deep moments in the fanfic, as his friends listen and support him, or sometimes are shocked by what he reveals.
Often, the exploration of Konan's unique paper - based jutsu is an interesting plot point. In many fanfics, she uses it in creative ways in battles alongside Naruto. For example, in some, she creates paper constructs to help Naruto with his training. Another is the development of their relationship. It could start as mutual respect and grow into a deep friendship or something more, like in 'Naruto and Konan: Unlikely Love' where they fall in love over the course of their adventures.
A possible interesting plot point is Naruto having to adapt his chakra control in the Martian atmosphere. Since Mars has different conditions than Earth, his jutsu might work differently. Another could be Naruto encountering Martian life forms and having to communicate or fight them using his ninja skills.