A 'narusaku naruto returns fanfic' could be about many things. It might focus on Naruto's return in a scenario where he has a relationship with Sakura. It could involve adventures they go on together, how their relationship has developed during his time away and his return, and how they face new challenges in the ninja world as a couple.
Well, it could be about a Naruto who has god - like powers and gets banished. Maybe he's too powerful for the village to handle, or perhaps there are some political reasons within the village that lead to his banishment. But without reading it, it's hard to say exactly.
In many Narusaku fanfics, Naruto might bring Sasuke back through the power of their friendship. Naruto's unwavering belief in Sasuke could be a key factor. He may constantly remind Sasuke of their past together, the bonds they formed as teammates in Team 7. For example, Naruto could recall the times they trained together, their shared dreams, and how they protected each other in battles. This could slowly chip away at Sasuke's resolve to stay away and eventually lead him to come back.
You can try looking on fanfic websites such as FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of fanfictions, and there's a good chance you'll find 'narusaku naruto returns fanfic' there.
One possible plot could be that Naruto leaves Konoha due to some misunderstanding. Maybe he feels unappreciated in his relationship with Sakura (Narusaku). He might go on a journey to find himself. Along the way, he could encounter new enemies and also make new friends who help him see things from a different perspective.
I think it's pretty far-fetched. The Rinnegan is not something Naruto would typically obtain, especially in a Narusaku context. It could make the story less believable and stray too far from the original canon.
Another theme is adaptation. He has to adapt to the new rules, cultures, and powers of the crossover world. For example, if it's a crossover with a magic - based world, Naruto has to learn how magic works and how to use it. This theme of adaptation makes for some interesting character development.
A 'Naruto get banished yaoi fanfic' is likely about Naruto being exiled from his village and then there are probably yaoi elements involved, which means male - male relationships. It could be about Naruto forming new relationships with other male characters during his exile.
Well, Naruto himself could be a really interesting take on a banished prodigy. Imagine if things had gone differently in the village and he was banished. It would be a huge change from the original story. Shikamaru is also a possibility. He's intelligent and has a lot of potential. If there was some sort of political or power struggle within the village that led to his banishment, it could make for an engaging fanfic. Also, Hinata could be a unique choice. Her shy nature but hidden strength could be explored in a banished prodigy storyline.