Often, Naruto and Sasuke are paired with Sakura Sensei in fanfiction. Since they are the main members of Team 7, many stories involve her interactions with them. For example, she might be teaching them new techniques or helping them deal with personal issues.
Well, some fanfictions might pair Sakura Sensei with the Hokage. The Hokage could be asking her for updates on Team 7's progress or seeking her advice on how to train the next generation of ninjas. Additionally, in some stories, she could be paired with other senseis from different teams. They might be having a friendly competition to see whose team is more skilled, and Sakura Sensei is determined to prove that Team 7 is the best.
Naruto is often paired with Ebisu Sensei in fanfiction. Since Ebisu was assigned to train Naruto at one point, many fanfictions build on that relationship, showing how Naruto grows under his tutelage and how Ebisu has to adapt to Naruto's unorthodox ways.
Kakashi and Evangeline could also be paired. Kakashi's cool and mysterious demeanor might intrigue Evangeline, and her vast magical power and long life experience could offer Kakashi new perspectives. They could have some interesting interactions as they are both quite powerful in their respective worlds.
In this fanfiction, Naruto is the key character as the sensei. For Team 8, Hinata is likely to be a major focus. Naruto might see a lot of his own insecurities in her and strive to help her become a stronger ninja. Kiba, with his energetic and sometimes brash nature, would provide a contrast to Naruto's more balanced approach, so he would be focused on for his development. Shino, with his unique abilities and quiet nature, would also be in the spotlight as Naruto tries to understand him better and help him integrate more with the team.
Well, the main characters usually start with Naruto. Then there are his students. They might be a diverse group. There could be a foreign exchange student from another ninja village, who has different abilities and a different view of the ninja world. Hinata could be involved too, maybe as Naruto's wife in the fanfiction and she helps him with the emotional side of teaching, like dealing with homesick students. And there could be a mischievous student who constantly challenges Naruto's patience and teaching skills.
Cthulhu is often paired with Nyarlathotep. Since they are both from the Lovecraftian mythos, their combined presence can create a much darker and more chaotic story. Another character could be Sherlock Holmes. The contrast between Holmes' rational mind and Nyarlathotep's otherworldly chaos makes for an interesting dynamic. Holmes would try to solve the mystery of Nyarlathotep's appearance and actions, while Nyarlathotep would be constantly trying to undermine Holmes' sanity.
Zoro is another popular character. He and Luffy have a strong bond, and in Gear 5 fanfiction, they might fight together in a new and more coordinated way. Zoro could be using his swordsmanship to complement Luffy's wild and unpredictable Gear 5 attacks, creating a powerful combination against their enemies.
Alice Angel is often paired with Baby Bendy. Their interactions can range from her being a sort of mother figure to him, guiding him through the dark and twisted world, to more complex relationships where they might have conflicting goals but still a connection.
Another popular character to be paired with the 'brother of Naruto' is Hinata. The brother could be protective of Hinata's relationship with Naruto or he could develop his own feelings for her, creating a love triangle situation which adds a whole new layer of drama to the fanfiction.
Chihiro is often paired with Haku in crossover fanfiction. Since they have an existing relationship in the original story, it's easy to expand on it in a crossover scenario, like in a modern - day AU (Alternate Universe) where they have to deal with new challenges together.
Luigi is often paired with Vampire Waluigi in fanfiction. Since they are counterparts in the original Mario universe, it creates an interesting dynamic in the vampire - themed stories.