A common theme could be friendship. Just like Naruto's relationships with his human friends, his bond with the nin cat could be about loyalty and mutual support.
One popular 'naruto has a nin cat' fanfiction might be on platforms like FanFiction.net. You can search there using relevant keywords like 'naruto' and 'nin cat' to find stories that match this concept.
The nin wolf might be a gift from a powerful ninja in the fanfiction. Maybe as a sign of Naruto's growing power or a new mission he has to undertake. It could also be a wild creature that Naruto tames during his travels.
Obviously Naruto is one of the main characters. His nin animal would also be a main focus. There might also be his friends like Sasuke and Sakura who interact with Naruto and his nin animal in different ways. Maybe Sasuke is initially jealous of Naruto's unique nin animal.
The nin wolf could make Naruto more respected among his peers. Other characters might see Naruto as having an even greater potential with this powerful ally by his side. Some might be a bit jealous, like Sasuke, who could see Naruto's nin wolf as another way Naruto is getting stronger faster.
Well, 'Naruto: The Nin Fox's Power Unleashed' is an interesting fanfiction. Here, Naruto gradually unlocks the full potential of the nin fox within him. This not only makes him stronger in battles but also changes the way other characters perceive him. There are also some fanfictions that explore the nin fox's backstory and how it ties in with Naruto's own journey, like 'Naruto and the Ancient Nin Fox Legacy' which dives deep into the history of the nin fox and Naruto's role in it.
In some fanfictions, the nin animal could have a connection to an ancient prophecy. So Naruto has to figure out how to use his nin animal in relation to this prophecy to save the village. Maybe the nin animal has a hidden form that is only revealed when certain conditions are met.
Sure, 'Naruto's Nin Fox Rebellion' has a really unique plot. In it, the nin fox inside Naruto starts to have a will of its own that doesn't always align with Naruto's. This creates a lot of internal conflict for Naruto as he tries to figure out how to deal with this new situation while still being a ninja. It's a fresh take on the typical Naruto - nin fox relationship.
The nin dog could change Naruto's life by making him more responsible. Since he has to take care of the dog, he'll have to think about someone else's needs. For example, he'll need to make sure the dog is fed, trained, and healthy. This will give him a new sense of purpose outside of his normal ninja training and goals.
If Naruto and Temari were missing nin in a fanfiction, it could start with a misunderstanding. Naruto might be framed for a crime he didn't commit and Temari, believing in his innocence, decides to help him escape. They then have to live on the run. Along the way, they meet other outcasts and form a sort of rebel group. Naruto's ability to make friends easily and Temari's strong leadership skills could be the driving force behind this new group's growth.