One idea could be a fanfic where a young ninja discovers a unique way to combine lightning jutsu with other elements like water, creating a new and powerful technique. This could lead to him being sought after by different clans for his knowledge.
First, do research on all the existing lightning jutsu in Naruto. This will give you a solid base for your fanfic. Then, create unique characters with their own relationships to lightning jutsu. For example, a character who fears lightning but has to learn lightning jutsu to protect their loved ones.
In fanfiction, the Lightning Dragon Jutsu can be extremely powerful. It can be depicted as a massive dragon made of pure lightning that can obliterate anything in its path. Another powerful one could be the Lightning God's Wrath, a jutsu that summons a bolt of lightning from the heavens with the power to level mountains.
He could develop a 'Lightning Clone Jutsu'. Instead of regular clones, these would be made of lightning. They could move at high speeds and deliver electric shocks on contact. Another jutsu could be 'Lightning Shield', where he surrounds himself with a layer of lightning for both offense and defense.
One great fanfiction could be 'Naruto's Lightning Ascent'. In this story, Naruto starts his journey to learn the Lightning Jutsu under Kakashi. Kakashi uses unique training methods that involve Naruto facing his fears in a lightning - filled dimension. It's a really interesting take on how Naruto could master this powerful jutsu.
Another idea for a Naruto Lightning Jutsu fanfiction is to explore the training aspect. How does a character learn to master lightning jutsu? It could be through rigorous training under a strict sensei. They might have to endure electric shocks while trying to control the chakra flow for lightning jutsu. This can add depth to your characters and show their growth over time.
Well, one key element is the mentor. In many of these fanfictions, Kakashi or another experienced ninja acts as the mentor. They guide Naruto through the process of understanding and controlling the lightning - based chakra. Another element is Naruto's motivation. Usually, it's either to become stronger to protect his friends or to prove himself to his village. For example, in some stories, Naruto wants to show that he can be as powerful as the other top - tier ninjas in the village.
Maybe Sasuke. Although they are rivals, they also have a deep bond. Sasuke might have come across a unique jutsu during his travels and decide to teach it to Naruto so that they can both become stronger and better protect their village.
He could practice in secret locations where no one can see him. For example, in an abandoned cave or a hidden part of the forest. That way, no one will know about the new jutsu he's developing.
It could be a new form of Rasengan. Maybe Naruto discovers a way to combine different elements with the Rasengan more effectively, like adding lightning to it for a more powerful and faster attack.