It could be Naruto himself. Since he has a connection to all the villages in some way, he could play a crucial role in the fanfic, perhaps as a mediator or someone who uncovers a hidden conspiracy during the summit.
Perhaps in the fanfic, a young shinobi manages to infiltrate the Five Kage Summit and has a significant impact on the discussions. This shinobi could bring new ideas or warnings that change the course of the kages' decisions. For example, he might have uncovered a plot by a rogue ninja group to take advantage of the kages being gathered in one place. This would not only create tension between the kages and the external threat but also among the kages themselves as they debate how to handle this unexpected situation.
In this fanfiction, Naruto might be pushed to attack the Five Kage Summit due to some misinformation or a threat he perceives to Konoha. Maybe he thinks the Kages are planning something against his village.
It could be a rogue ninja who has a vendetta against all the villages represented at the summit. He might have been wronged in the past by the combined actions of the five great villages and now seeks revenge. He could use the chaos of the summit to launch attacks and try to undermine the stability of the shinobi world.
In a 'naruto five kage summit fanfiction', a great plot could be that the Mizukage reveals she has evidence of a traitor among the other Kages' entourages. This leads to a tense investigation during the summit, with accusations flying and old grudges resurfacing. The story could explore how the Kages balance their trust in their own people and the need to maintain diplomatic relations during such a crisis.
The fanfiction might explore Dark Naruto's motives during the Kage Summit. He could be on a mission to expose the secrets that the Kages have been hiding from the shinobi world. His actions at the summit could be a way of shaking up the established order. For example, he might reveal a conspiracy among the Kages that has been affecting the balance of power in the ninja villages. This would not only put the Kages in a difficult position but also force the other shinobi present to re - evaluate their loyalty.
One interesting Kage Summit Naruto fanfiction could be one where Naruto has a secret plan during the summit that no one anticipates. He might use his charm and newfound diplomatic skills to sway the Kages in a direction that benefits the entire shinobi world.
In a 'Dark Naruto Kage Summit' fanfiction, it's possible that Dark Naruto is actually a misunderstood figure. He arrives at the summit not to cause destruction but to seek help. His dark transformation might be the result of an experiment gone wrong that he had no control over. The Kages, initially seeing him as a threat, might come to realize his true situation after he reveals his story. This could lead to a different kind of relationship between Naruto (even in his dark state) and the Kages, where they work together to find a solution to his problem.