One idea could be Boruto traveling back to the era of the First Hokage. He could witness the founding of Konoha and interact with the original founders. Maybe he tries to prevent a certain event that he knows will have long - term negative consequences in his own time.
A more personal plot could be Boruto traveling back to a time when his father, Naruto, was a young boy. He could see Naruto's struggles and hardships up close and gain a new understanding and respect for him. He might also try to help Naruto in some small ways without revealing his true identity, like leaving behind some useful ninja tools or giving him advice in a disguised way.
Another plot could involve Boruto and his friends traveling back to a time when a great war was about to start. They could use their knowledge of future ninja techniques to change the course of the war, but also face the challenge of not changing history too much as it might erase their own existence. For example, they might try to save a key figure who was supposed to die in the original timeline.
Another interesting plot could be about a new villain that is a combination of the powers of all the previous villains in Naruto and Boruto. The characters would have to team up in new and unexpected ways to defeat this powerful foe. For example, Naruto and Boruto might have to combine their Rasengan and Vanishing Rasengan in a completely new way.
A possible plot could involve a time - travel situation. Boruto and Mitsuki get sent back in time to the era of the First Hokage. There, they have to adapt to the different ninja world of that time. They meet the young versions of their ancestors and get involved in events that could change the future. This would test their knowledge of ninja history and their skills as they try to find a way back to their own time without disrupting the past too much.
Another plot idea could be a crossover within the Bloodstained Arc world. For example, two groups or characters that have never interacted before are forced to team up against a new, powerful enemy. This could lead to interesting character dynamics and development.
It could be a time - traveling rogue ninja from the future who has his own plans to change history for his own benefit. He might want to take over the ninja world in the past so that he can rule in the future without any opposition.
A story could be set in a future where Boruto has become a great ninja and Himawari is training hard. Boruto takes on the role of a mentor to Himawari for a while. They embark on a mission together to stop a powerful enemy who is threatening the peace of the ninja world. Along the way, they learn more about each other's strengths and weaknesses and their relationship evolves.
A plot where Naruto and Boruto have to team up to fight a new, powerful enemy that neither could defeat alone. This would allow for some great father - son bonding moments and also show how their skills complement each other. For example, Naruto's brute strength combined with Boruto's unique ninja techniques. It could also explore how Naruto imparts his wisdom about the ninja way to Boruto during the battle.
Maybe a fanfic where Naruto and Boruto are pitted against each other in a virtual reality battle. It could be part of a training exercise that gets out of control, and they start using their real skills and emotions, leading to a intense and revealing fight.
One idea could be a time - travel plot where Sarada goes back in time and meets a young Naruto. She could learn from his experiences and determination, and in turn, she might influence some of his decisions. This would create an interesting dynamic as they come from different generations but share common goals of protecting the village.
A possible plot idea is that Shinachiku is targeted by a group of rogue ninjas who think he has some valuable information. Boruto then has to protect him while also trying to figure out what these rogues are after. Another aspect could be that Shinachiku wants to prove himself to Boruto by taking on a difficult task on his own, but gets in over his head and Boruto has to come to the rescue. There could also be a plot where they both go on a journey to find a rare ingredient for a medicine that is needed to save someone in the village.
Well, perhaps a story where Boruto and Himawari accidentally swap their abilities for a day. Boruto has to deal with Himawari's gentle nature and her unique skills, while Himawari has to adapt to Boruto's more energetic and combat - oriented skills. This could lead to some really funny and heartwarming moments between them as they learn more about each other.