Maybe Naruto discovers that his cancer is a key to unlocking some ancient power. So instead of it being just a death sentence, it becomes a journey of self - discovery and a way to become even stronger in a different sense. He could have to go on a quest to find the right knowledge to use this new - found connection.
Another plot twist could be that the medical ninjas in the village find a way to transfer Naruto's cancer to an inanimate object, but in doing so, they accidentally create a monster that is now a threat to the village. So Naruto now has to deal with the consequences of being cured in an unexpected way.
It could turn out that the cancer is just an illusion created by a powerful enemy to break his spirit. Once he realizes this, he has to fight not only to regain his physical health but also to overcome the mental trauma of believing he was dying.
A plot twist might be that Anko was once in love with someone else, and that person suddenly returns. Naruto would then have to compete not just with his own insecurities but also with this new rival. Or, it could be that Naruto's crush on Anko is part of a genjutsu placed on him by an unknown enemy. When he breaks free from the genjutsu, he has to re - evaluate his feelings for Anko, and Anko has to deal with the fact that Naruto's feelings were not entirely real at first.
A plot twist could be that Naruto finds out through Tobirama's memories that there was a secret alliance that Tobirama had made with another village long ago, and this alliance was supposed to be kept hidden. But now, Naruto has to figure out how to handle this information without causing chaos between the two villages. Another possibility is that Tobirama's memories show Naruto a different side of some of the village elders, a side that is more sinister. This could make Naruto question who he can really trust in the village and lead to a whole new set of power struggles and investigations within the fanfiction.
Perhaps Naruto discovers that Kisame has a family he's been protecting in secret, and this new knowledge makes Naruto see Kisame in a different light. He then tries to help Kisame reunite with his family while also dealing with the Akatsuki.
Perhaps Naruto discovers that Sheele was sent to his world by an enemy as a spy, but she has actually fallen in love with the place and the people, especially Naruto, and she has to prove her loyalty. This would create a lot of drama and tension in the story.
A possible plot twist could be that Tsuyu is secretly related to one of Naruto's enemies. Maybe she discovers this during the course of a mission and has to decide whether to side with her newfound family or continue to be Naruto's ally.
One possible plot twist could be that Naruto was cloned by an enemy to infiltrate the Leaf Village. But as he grows up, he starts to develop his own sense of self and loyalty to the village, causing a conflict within him. Another could be that the real Naruto is actually alive somewhere else, and the clone Naruto has to find and reunite with his original self.
One possible plotline could be Naruto struggling to keep his ninja duties while dealing with the illness. He might try to hide it from his friends at first. Another could be him seeking out rare medical ninjutsu or herbs to cure himself. Maybe he teams up with some unlikely allies in his search for a cure.
A possible plot twist could be that Naruto discovers he has a hidden connection to Smaug. Maybe he is related to Smaug in some long - lost magical way. Another twist could be that Smaug is not really a villain in this fanfiction. Instead, he is being controlled by a greater evil, and Naruto has to figure out how to free Smaug from this control. It would change the whole dynamic of their relationship from one of enmity to a more complex situation where they could potentially become allies.
A possible plot twist could be that Naruto turns out to be a keyblade wielder in disguise. This would completely change the dynamic as everyone in the Naruto world and Kairi would be shocked. It could also mean that Naruto has a whole different origin and mission related to the world of Kingdom Hearts.