Perhaps there could be a story where Naruto's chakra is seen as a unique form of energy in the Star Wars universe. The Sith see it as a means to enhance their dark side powers. They manipulate Naruto, showing him false visions of his past failures in Konoha, which makes him angry and more susceptible to the allure of the dark side.
One idea could be Rey being lured to the dark side by a powerful Sith artifact. Maybe she discovers an ancient Sith holocron that shows her a version of the galaxy where the dark side rules supreme and she starts to believe that it's the only way to bring true order. Another plot could involve Rey being manipulated by a dark side user who preys on her insecurities about her past and her power.
In a fanfiction, Ezra might be tricked into joining the dark side by a disguised dark side user. This person could pose as a friend in need, only to lead Ezra down a dark path. They could manipulate his insecurities and his desire to be a stronger Jedi.
Another concept could involve characters from Star Wars being brought into the Naruto universe during the time when Dark Naruto exists. For example, a Jedi like Obi - Wan Kenobi could try to understand and potentially redeem Dark Naruto, seeing similarities between the dark side of the Force and Naruto's own inner darkness. This could lead to an interesting dynamic as Obi - Wan tries to use his Jedi teachings to reach Naruto.
One idea could be exploring the life of a new Jedi who emerges during the Dark Empire era. They could start as a hidden Force - sensitive on a remote planet and then get drawn into the conflict between the remnants of the Empire and the New Republic. Another plot could focus on the dark side artifacts that are being unearthed during this time and how different factions are trying to control them. Or perhaps a story about a group of smugglers who accidentally get caught in the middle of the power struggle between the Empire and the Republic and have to use their wits to survive.
One idea could be exploring the backstory of a new, powerful Sith Lord in the Dark Destiny universe. Maybe this Sith Lord was once a Jedi apprentice who fell to the dark side due to a great betrayal. Another could be focusing on a group of rebels trying to find a long - lost Jedi holocron that holds the key to defeating the dark side once and for all in this fanfiction setting. A third idea might be a story about a young Force - sensitive character who is caught between the light and dark side, being courted by both the Jedi and the Sith.
If Naruto turned to the dark side in a Star Wars fanfic, his shadow clone jutsu could be used in a very menacing way. He could send shadow clones to infiltrate Jedi or Sith strongholds. His Rasengan, with the added dark side energy, might become a more destructive and unpredictable force, like a mini - black hole of sorts in the Star Wars context.
Here's another plot. In the fanfiction, a group of Sith Lords discovers the Naruto world and decides to use the powerful ninja there for their own evil purposes. A senator in the Star Wars universe, who has some knowledge of the Naruto world, tries to stop them. He teams up with some of the Naruto characters, like Naruto himself or Kakashi. Together, they embark on a journey across both universes to defeat the Sith Lords and protect both the Star Wars galaxy and the Naruto world from destruction.
A plot idea could be that the Sith Lord somehow discovers the power of chakra and tries to use it to create an ultimate weapon. Naruto and his friends, along with the Star Wars Rebellion, have to stop him. They travel across different planets and Hidden Villages to gather knowledge and allies.
One idea could be Naruto and Hinata as Jedi knights. They could go on a mission to save a planet from the Sith. Naruto's strong willpower and Hinata's gentle yet firm nature would make them great Jedi. Another plot could involve them being part of a resistance against the Galactic Empire, using their unique ninja skills in a Star Wars setting.
Well, perhaps there could be a story where a character with Sharingan - like abilities (similar to Sasuke in Naruto) in the Star Wars universe is a Jedi. He is betrayed by his master who turns out to be a Sith in hiding. The master wants to take the young Jedi's unique powers for himself. In a different scenario, a group of Naruto characters are on a mission in the Star Wars world and one of them is bribed by the Trade Federation to betray the rest. This could lead to a series of battles and the Naruto characters having to find a way to overcome the betrayal and the new threats they face.