Well, a great storyline might be that Naruto and Kakashi enter a mysterious forest that has some sort of ancient power. In this forest, they have to solve puzzles and fight off strange creatures. As best friends, they support each other throughout the ordeal. They also have deep conversations during their journey, like about Kakashi's relationship with Obito and Naruto's feelings for Sasuke. It would be a story full of adventure and friendship.
There could be a fanfiction where Naruto and Kakashi participate in a friendly ninja tournament against other villages. But there's a catch - they have to team up with a couple of unruly and difficult ninja from other villages. Naruto and Kakashi have to use their friendship and teamwork skills to not only win the tournament but also to teach their new teammates the value of cooperation. Along the way, they face various challenges that test their bond and their ninja abilities.
One interesting storyline could be Kakashi taking on a more fatherly role towards baby Naruto. He could teach Naruto some basic ninja skills from a very young age, like how to throw a kunai properly. This would create a strong bond between them early on.
One interesting storyline could be them training together for a new and powerful jutsu. Naruto's unorthodox methods combined with Lee's intense discipline would create a unique training session. They might face challenges like finding the right balance between Naruto's chakra - based techniques and Lee's taijutsu - only style. Another could be them going on a mission to a far - off land where they have to rely on each other's strengths. Naruto's quick thinking and Lee's physical prowess would be put to the test as they encounter various enemies and obstacles. They could also have a storyline where they help each other overcome personal issues. Naruto could assist Lee in dealing with his insecurities about not being able to use ninjutsu, while Lee could help Naruto control his temper and focus better in battles.
One storyline could be Naruto and Gaara teaming up to take on a new and powerful enemy that threatens both their villages. They combine their unique skills, Naruto with his Rasengan and Gaara with his sand control, and through their friendship, they learn to trust each other even more during the battle.
Perhaps a storyline where the apprentice discovers a new jutsu and has to keep it a secret while they master it. They could struggle with whether or not to tell Kakashi, fearing disappointment if they fail. This adds an element of internal conflict.
A more emotional storyline could be that Shino is feeling left out because of his rather quiet and strange abilities compared to others. Naruto, being his best friend, helps him see the value in his skills. He could encourage Shino to show off his insect techniques more, and together they participate in a ninja competition where Shino finally gains the recognition he deserves, all thanks to Naruto's support.
There could also be a storyline where Naruto and the Kyuubi team up to face a common enemy that neither of them could defeat alone. They have to rely on each other's strengths, with Naruto's determination and the Kyuubi's raw power. This adventure would bring them closer as friends and show the world that they are a force to be reckoned with.
Perhaps in the fanfiction, Kakashi is influenced by a dark power. This power corrupts his mind and makes him turn on Naruto. It could be related to some ancient curse or a new enemy's ability that targets Kakashi's mental state. Naruto, being the target, would then be at the mercy of Kakashi's attacks, creating a lot of drama and conflict in the story.
One interesting storyline could be them teaming up against a new supervillain that neither can defeat alone. They combine their unique skills, Superman's super strength and flight with Batman's detective skills and gadgets.
One popular storyline could be Anbu Kakashi being assigned to secretly protect Naruto during a dangerous mission. This could involve Kakashi using his stealth skills to keep Naruto safe while Naruto is unaware, and later Naruto discovers the truth and a bond between them deepens.
Perhaps a storyline where the apprentice gets involved in a mission that was originally meant for Kakashi. This could lead to the apprentice having to prove themselves not only to their teammates but also to Kakashi. They might encounter powerful enemies and have to use their wits and the skills they've learned from Kakashi to survive. In the process, they could also discover some secrets about Kakashi's past that helps them better understand their master.