There's a fanfic called 'Gabimaru and Sagiri: The Unlikely Alliance'. In this one, they start off as reluctant partners but gradually form a deep connection. The author does an amazing job of showing Gabimaru's protective side towards Sagiri and how Sagiri comes to respect Gabimaru's skills and determination. It has some really intense and emotional scenes that make it a great read.
Characterization is key. A good Gabimaru x Sagiri fanfic should accurately portray their personalities. Gabimaru is tough yet has a soft side, and Sagiri is strong - willed and determined. If the fanfic can show how they complement each other, it's great. For example, Gabimaru's combat skills and Sagiri's strategic mind working together.
A common theme is the exploration of their relationship growth. Since they come from different backgrounds, fanfics often show how they overcome differences.
One place to find gabimaru x sagiri fanfiction could be Archive of Our Own (AO3). There are often many well - written fanfics there. You can search for the specific pairing and then sort by popularity or rating to find some great reads.
Perhaps it's a shinobi who has retired after a long and eventful career. He could be someone who has seen the darker side of the shinobi world and wants to make sure Naruto doesn't go down the wrong path. He might have been a wandering shinobi who finally settles down with Naruto. For example, he could be a shinobi from a different village who has a unique set of skills to teach Naruto.
One of the best shinobi novels could be 'Naruto'. It has a richly detailed world of ninjas, with complex characters like Naruto Uzumaki. The story follows his journey from an outcast in his village to a hero, filled with action, friendship, and the exploration of ninja values.