One thing I think ANBU naruto stories get wrong is when they make him older. When you have a character age in your story, you have to understand, logically, how they would act. For example, I've been thinking of a ANBU naruto story where naruto is literally the chosen one. Created, not born, because God loved him so much. But his body can't handle all the power he has, so as a kid, he blows up ANBU kushina puts him in the ANBU to manage his powers. He's the oldest of 3, with a twin sister and a brother, and eventually later down the line, an adopted little sister. He's protective because he's strong. He's responsible becauses he's the first born, but he's still naruto, so he's reckless and does what he wants.
When you take a child like this and put him in the ANBU, fighting and killing, with friends and allies, and people he looks up to, having a good time, the weight of his actions isn't going to hit him until everybody from his Anbu is gone. He's going to have to mature later than his peers, but at a faster rate. He's going to want to quit and retire in his early 20s because a being this strong makes everyone else lazy, and he does too much work. He's going to be nostalgic and tell war stories because everybody he knew in his time, in his you know 15+ years of being in the ANBU, is dead or retired. At 25, he'll be 40, and at 40, he'll be your grandpa.
Its your character, but that doesn't mean you can do what you want with them, you wrote them a specific way, you have to know how this will effect them in the future
