One interesting plotline could be Naruto and Sasuke going on a journey together outside of the Hidden Leaf Village to explore a new land filled with strange creatures and unique ninja techniques. They could face challenges that force them to rely on their friendship more than ever.
Another plotline could involve time - travel in the fanfiction. Naruto and his friends could be sent back in time to the era of the First Hokage. There, they would have to adapt to the different ways of the past while also trying to figure out how to get back to their own time, and in the process, they might change the course of ninja history.
One possible plotline could be that Naruto has to go through a series of dangerous trials in the enemy's territory to reach Sasuke. He might face powerful foes and have to use new jutsu he's developed. Another plotline could be that Sasuke is in a coma, and Naruto uses his chakra to somehow enter Sasuke's mind and fight off the inner demons that are keeping Sasuke trapped. Maybe Naruto also has to convince Sasuke's friends from his time away to help him in this rescue mission.
One interesting plotline could be Naruto and Sasuke initially resisting the forced marriage but then gradually realizing they have a deeper connection they never noticed before. They might start to understand each other's pain and dreams better through this unexpected situation.
One interesting plotline could be Naruto and his friends traveling back in time to prevent a great tragedy that happened in their world. For example, they might go back to stop the destruction of a village.
Another plotline might involve Naruto inviting Gaara to Konoha for a festival. Gaara, who is not used to such lively and friendly atmospheres, starts to open up more. He gets to interact with Naruto's friends like Sakura and Shikamaru, and through these interactions, he discovers new aspects of friendship and the joys of a more carefree life. This also helps the two friends understand each other better outside of their ninja duties.
Another plotline could involve a new character who befriends Sasuke. Naruto, being the competitive and close friend that he is, might get jealous of their budding friendship. This could lead to Naruto trying to insert himself into their activities and causing some comical or tense situations.
In some fanfictions, the plot could involve the entire Konoha village coming together to support Naruto in his mission to bring Sasuke back. They could pool their resources, knowledge, and skills to help Naruto find Sasuke. Along the way, Naruto might learn more about the secrets of the Uchiha clan from the elders in Konoha, which gives him an edge in convincing Sasuke to come home.
Another plotline might involve an alternate universe where Naruto and Sasuke are not from the same village. They meet as strangers in a foreign land and initially have a hostile encounter. But as they get to know each other better, they discover that they have more in common than they thought, and a romantic relationship begins to develop.
In some 'naruto retrieves sasuke fanfic', there could be a plot where Sasuke himself is in a moral dilemma. He might not be fully against being retrieved, but his pride and his own goals are holding him back, adding an interesting layer to Naruto's mission.
A plotline where Sasuke and Kakashi are forced to team up against a new and powerful enemy that neither of them can face alone. They have to put aside their differences and combine their unique skills. For instance, Sasuke's Sharingan and Kakashi's Sharingan - related techniques could be combined in a creative way to defeat the foe. This would involve a lot of strategizing and character development as they learn to trust each other more.