A really interesting plot twist could be that the whole concept of 'evil' is a facade. Naruto, as the godson of what is thought to be evil, might find out that Sarutobi was actually in league with this 'evil' all along. They were working together to bring about a new order in the ninja world. But as Naruto grows, he has to decide whether this new order is truly good or just another form of tyranny. He could then use his unique position to either support or oppose Sarutobi and the so - called 'evil'.
Naruto would likely be more conflicted. Instead of his usual cheerful self, he'd constantly struggle with the idea of being associated with 'evil'. He might be more withdrawn at first, not sure how to handle this new identity.
Well, a plot twist could be that since Naruto is Hiruzen's son, the Akatsuki targets him differently. Instead of going after the Nine - Tails inside him in the usual way, they might try to use his relationship with Hiruzen against him. They could try to blackmail Hiruzen into making certain concessions for the safety of his son. Also, Naruto's training might be more intense and different. He might be taught more about the political side of being a ninja by Hiruzen himself, which changes his perspective on the ninja world.
One possible plot twist could be that Narcissa uses her influence as Harry's godmother to protect him from the darker forces within the wizarding world in a more public way than in the original series. For example, she might openly oppose Voldemort's regime to save Harry, which would put her in a very dangerous position as she was once part of the Death Eater families.
One possible motivation could be to create drama. By having Naruto kill Sarutobi, it would shock the readers and create a huge rift in the story's world. It might also be a way to explore Naruto's dark side that we rarely see in the official story.
Another plot development could be that with Sarutobi as his adoptive father, Naruto has access to different mentors. Sarutobi could call in favors from other great ninjas to train Naruto. This would expose Naruto to a wider variety of fighting styles and strategies. Maybe he gets trained by Kakashi earlier, or even has the chance to learn from some of the retired or older ninjas who usually keep to themselves.
In this type of fanfiction, it's possible that the story delves into Naruto's backstory and how being Sarutobi's son would have affected his childhood. Maybe he would have grown up with more guidance and support, which could have changed his personality. Instead of being the lonely outcast that he was in the original story, he could have been more confident from the start. The fanfiction might also introduce new characters related to Sarutobi that play important roles in Naruto's life. There could be new adventures and challenges that are unique to this new family dynamic, such as Naruto having to uphold the Sarutobi family name and legacy within the Hidden Leaf Village.
Perhaps the plot could involve Sarutobi protecting Naruto from the more malicious elements in the village. He could use his influence to ensure Naruto has a normal childhood, or as normal as it can be for a jinchuriki. Naruto might also inherit some of Sarutobi's wisdom and leadership skills, which would be important for his future development.
Well, it could be about Naruto getting special training from Sarutobi in stealth. Maybe Sarutobi teaches Naruto some ancient jutsu that only he knows. This would give Naruto an edge in battles and make him more respected in the village.
One possible plot twist could be Hermione getting tired of being overlooked in the wizarding world despite her intelligence. She might turn to the Dark Arts out of a sense of vengeance. For example, she could start using her knowledge of spells to manipulate those who have underestimated her, like some of the pure - blood supremacists. Maybe she'd form her own group of followers who are also disillusioned with the current state of the wizarding world order.
Perhaps Naruto discovers some long - lost teachings or secrets of Sarutobi and goes on a journey to master them. This could lead to him facing various opponents who also want those secrets for their own evil purposes. He would then have to protect Sarutobi's legacy while also growing as a ninja.