Jiraiya could be an interesting assassin master. He already has a lot of knowledge and skills that he could pass on to Naruto in a more assassin - like way. His experience in espionage and combat would make him a great fit.
One main theme is often power and its acquisition. Naruto, as an assassin, is constantly seeking to gain more power to achieve his goals, whether it's protecting his village or avenging someone. Another theme is secrecy. Since assassins operate in the shadows, there's a lot about hiding identities and motives.
Maybe the assassin master has a hidden past related to Naruto's family. So, the story could revolve around uncovering this mystery while Naruto trains under him. This would add depth to Naruto's character development as he learns about his family's secrets.
One popular 'naruto master assassin fanfiction' is 'Naruto: The Assassin's Creed'. It combines the world of Naruto with elements of the Assassin's Creed franchise, creating an exciting and unique story. Another one could be 'Naruto: Shadow Assassin', which often features Naruto with enhanced assassin - like skills and stealth abilities.
It could be a former Auror who has turned to more shadowy ways of dealing with threats. After seeing the inefficiency of the Ministry's methods in some cases, they decide to take matters into their own hands and become a sort of assassin to target dark wizards.
One possibility is that Naruto uses his shadow clone jutsu in a new and devious way for assassinations. He could send clones to gather intelligence, and when the time is right, he strikes with his signature rasengan in a stealthy manner. Maybe he would also learn new techniques from the world of assassins, like silent movement or poison use, all while still maintaining some of his ninja values like protecting his friends and village.
His relationship with Sasuke would be very different. Instead of just competing in terms of strength, they might become rivals in the world of assassination. Sasuke's own dark path could either align or clash more intensely with Naruto's new role. And with Sakura, Naruto might be more distant as he delves deeper into the assassin world. She might be worried about the changes in him.
Well, it depends on the specific fanfiction. There are countless Naruto fanfictions out there, and each author has their own vision. While the original Naruto is far from a cold assassin, in the realm of fan - created stories, the possibilities are endless. Some fanfictions might do this to add an element of shock or to explore a more edgy and mature version of the Naruto character.
Sasuke could be a likely candidate in a sense. Given his skills as a ninja, his Sharingan which gives him an edge in combat and perception, and his past as a sort of 'rogue' ninja. He could be in a situation where Naruto has to hire him for a special mission that requires his unique abilities. Another possibility is Kakashi. He has a vast array of skills, is very intelligent, and could easily take on the role of an assassin if needed, even if it goes against his normal moral code slightly. He would do it for Naruto's sake.
It depends on your taste. If you like the idea of Harry Potter in a completely different and edgier role like an assassin, it could be interesting. However, some purist fans might not like this deviation from the original concept of the series.