Perhaps there could be a storyline where Naruto discovers he is an elf through some mysterious event. His journey then becomes about learning about his elf roots, like the history and culture of elves in this fictional setting. He might also have to face an evil force that is threatening both the elf and ninja worlds, and use his combined skills from both identities to save the day. Along the way, he could form alliances with other unique characters, some from the elf side and some from the ninja side, and develop new techniques that blend elf magic and ninja jutsu.
One possible storyline could be Naruto as an elf trying to fit into the ninja world while still having his elf heritage. He might face discrimination from some who don't understand his different nature.
One possible storyline could be that Fenris is initially suspicious of the Elf Inquisitor due to their different backgrounds and the power the Inquisitor wields. Maybe they meet during a skirmish against a common enemy, like a group of darkspawn. Fenris sees the Inquisitor's combat skills and starts to respect them. As they interact more, they find they have common goals in terms of protecting the world from various threats.
One possible storyline could be that Naruto is chosen as a temporary Kazekage due to a threat that requires his unique skills. He then has to deal with internal conflicts within the Sand village while also facing external enemies. Another could be that there is some kind of prophecy that only Naruto can fulfill as Kazekage to save both Konoha and Suna.
In a Naruto and Derieri fanfiction, a possible storyline could be that Derieri is mistaken for an enemy in the Naruto universe. Naruto, being the one to see her potential for good, tries to convince others that she is not a threat. As they try to clear her name, they uncover a conspiracy that threatens both their worlds. This would involve a lot of mystery - solving and action as they race against time to stop the conspiracy.
There could be a storyline where Naruto, as a fan of the 4th Hokage, gets to time - travel back to the era of the 4th Hokage. There, he could interact with his father, learn from him directly, and even help him in some of his battles. Or maybe Naruto tries to prove himself worthy of being the 4th Hokage's successor in a more intense and unique way compared to the original story.
Perhaps Naruto becomes a vigilante after being wrongly accused of a crime he didn't commit. As a result, he goes into hiding and starts operating from the shadows. He could then use his skills and knowledge to not only clear his name but also expose the real culprits behind the false accusations and other corrupt elements in the ninja world.
One possible storyline could be how the Hidden Leaf Village copes with his death. Maybe there are power struggles as different clans vie for leadership in the absence of Naruto's unifying presence.
One possible storyline could be that Kalawarner somehow ends up in the Naruto universe. She might be confused at first but then use her own skills to help Naruto and his friends in a battle. Maybe she has some unique powers that are useful against a new enemy.
Perhaps in the fanfiction, Madara's neglect leads him to explore ancient and forgotten jutsu. He could use these newly discovered powers to show the ninja world what they've been missing by ignoring him. This could involve him making a grand display of his strength to gain the respect he believes he deserves.
In such a fanfiction, one possible storyline could be that Naruto is somehow mind - controlled and attacks Konohamaru without his own free will. Another could be a situation where there is a huge misunderstanding, like Konohamaru is framed for a serious crime against the village and Naruto, in his overzealous sense of justice, takes extreme action. However, this goes completely against the character development and the bond they have in the original series.
A possible storyline could be a time - travel one. Maybe Naruto travels back in time to the Star Wars era and meets Princess Leia. They then work together to prevent a dark force from taking over the galaxy.