One interesting plot idea could be a villain using hypnosis to turn Naruto's friends against him. This would create a lot of internal conflict for Naruto as he has to figure out how to break the hypnosis and regain their trust.
Another plot could involve a mysterious character who uses hypnosis to make Naruto forget his own identity. As Naruto tries to piece together who he is, he uncovers secrets about his past and the origin of his powers. This would be a great way to explore his character in a different light and introduce new story elements.
Maybe in a naruto hypnosis fanfic, Naruto himself discovers the power of hypnosis. He could use it in a unique way during battles, like hypnotizing opponents to see illusions of their worst fears, giving him an edge in combat. It would be a new and unexpected power for him to develop.