One interesting plot could be that Boruto accidentally travels back in time and meets Neji. At first, Neji is on guard, thinking Boruto is an enemy. But when Boruto explains his situation, Neji decides to help him get back to his own time. Along the way, they face some common enemies. Boruto shows Neji some of his unique abilities, and Neji teaches Boruto some of his wisdom and combat skills.
In a 'Boruto meets Neji' fanfiction, the plot could revolve around a mystery that only they can solve together. Let's say there is a strange power emerging in the Hidden Leaf Village that is related to an ancient Hyuga technique that Neji knew. Boruto teams up with Neji to figure out what's going on. During their investigation, they have to face off against some powerful foes. Neji's experience and Boruto's creativity combine to overcome the challenges, and in the process, Boruto gains a new mentor and friend in Neji.
Perhaps in this fanfiction, Neji is brought back to life somehow. Boruto, being curious, approaches Neji. Neji then discovers how much the ninja world has changed since his time. Boruto could show Neji the new technology in the Hidden Leaf Village. Neji might be a bit shocked at first but then start to see the potential in these new things. They could also form an unlikely friendship, with Neji guiding Boruto in matters of honor and discipline, which are values Neji held dear.
Their interaction could change the plot significantly. For example, if Neji teaches Boruto a new jutsu, Boruto could use it to defeat a powerful enemy. This would then shift the balance of power in the story.
One possible interesting plot could be Naruto and Boruto getting transported to a parallel dimension where their roles are reversed. Boruto has to deal with the challenges Naruto faced in the past, like fighting powerful villains without the advanced technology he's used to. Meanwhile, Naruto gets to experience the modern ninja world from Boruto's perspective, including the new ninja tools and different social dynamics in the Hidden Leaf Village.
If Boruto meets Neji in a fanfic, it could also have an impact on Boruto's view of the ninja world. Neji had a complex view of the world due to his own upbringing. His insights could make Boruto think more deeply about things like destiny and hard work. Maybe Neji could even give Boruto some advice on how to deal with his enemies in a more strategic way.
One idea could be Boruto getting transported back in time and meeting a young Naruto. He could then help Naruto avoid some of the early hardships he faced, but also realizes that those hardships made Naruto who he is. Another could be Naruto and Boruto switching bodies for a day, which would lead to humorous situations as they try to navigate each other's lives. A third idea might be that Boruto discovers a hidden power within himself by training with Naruto in a special dimension where time moves differently.
Maybe in the fanfiction, Jiraiya is summoned by a new jutsu gone wrong. When he meets Boruto, he mistakes him for Naruto at first. As they interact, Jiraiya realizes Boruto's own unique struggles. He shares his wisdom about handling the expectations that come with being a ninja from a famous family, and Boruto learns a great deal from him.
One plot idea could be a story where Sakura and Neji are paired on a mission in a foreign land. They have to rely on each other's skills to survive and in the process, they discover new aspects of each other's personalities. For example, Sakura's medical skills might save Neji from a deadly poison, and Neji's Byakugan helps them avoid hidden traps.
One idea could be that Neji discovers a new hidden power within Naruto that he helps Naruto master. This could lead to them having to face a new, powerful enemy together.
Another plot could be that they discover their pregnancies around the same time and decide to support each other in their respective journeys. They might share their fears and hopes, like Hinata being worried about how her child will fit into the Hyuga clan's strict hierarchy and Neji being concerned about providing a good future for his child. They could then work together to change some of the old ways in the clan for the betterment of their future children.
One interesting plot could be that Neji and Sakura are paired up for a school project. They start off not getting along because of their different personalities. Neji is more reserved and serious, while Sakura is bubbly and determined. But as they work together, they begin to understand each other better and form a friendship that could potentially turn into something more.