Naruto's personality would adapt to fit the new role. His existing positive traits like his courage and his ability to make friends would help him in the Green Lantern Corps. He'd be more of a team player perhaps, learning to work with beings from all over the universe. His impulsive nature might still be there, but he'd learn to control it better with the discipline that comes with being a Green Lantern. And his overall goal would shift from becoming Hokage to being a great Green Lantern and protecting the cosmos.
His already positive personality would become even more so. He'd be like a beacon of hope. He might be more focused on bringing out the best in others, since that's what Blue Lanterns do.
Naruto's character would gain a new sense of responsibility. As a Green Lantern, he'd have to abide by the Corps' rules and uphold justice on a much larger scale. This might make him more serious at times, but his core of being a fun - loving and determined person would still remain. He'd also learn to work in a team with other Green Lanterns, which could be different from his experience with his ninja teams as they come from diverse backgrounds.
His physical abilities would likely be enhanced. Red Lanterns have increased strength, speed, and durability. Naruto already has great physical prowess as a ninja, but as a Red Lantern, he could become even stronger. His ninjutsu might also change. For instance, his rasengan could be infused with red energy, making it more powerful.
If Naruto were to become an angel in fanfiction, his personality would experience a significant transformation. His boisterous nature might be toned down a bit as he takes on a more solemn and wise demeanor. He would still be the kind - hearted Naruto we know, but his understanding of good and evil would be deeper. His compassion would extend not only to his friends and villagers but also to his enemies. He would strive to redeem them rather than simply defeat them, seeing the potential for good in everyone, which is a very angel - like trait. His sense of justice would also be more refined, based on a celestial understanding of right and wrong rather than just the ninja code.
Naruto might become more reserved. Princes are often expected to be composed, so he'd have to tone down his exuberant nature. But he'd still keep his kind heart.
Naruto's perception abilities might improve. The Green Lantern ring gives the user access to a lot of information. He could use this to detect enemies more easily, similar to how he uses his sage mode to sense chakra. Also, his ability to communicate and connect with others could be different. He might be able to use the ring to communicate across long distances, which would be useful in both his ninja world and in any Green Lantern - related scenarios.
His mobility would be enhanced. He could fly around like Green Lanterns do, which is a huge change from his normal ninja running and jumping. He could also use the ring to create shields, protecting himself from attacks that his ninja gear might not be able to handle.
Naruto's usually positive and energetic personality would likely become darker. He might be more brooding as a Death Knight. His sense of humor would probably be tinged with a bit of morbidity. However, his core of loyalty and protectiveness would still remain, just expressed in a different way. For instance, he would be more willing to use extreme measures to safeguard his village and friends.
If Naruto becomes a hunter nin in the fanfic, his sense of justice could become more complex. As a hunter nin, he'd be exposed to different shades of right and wrong. He might not be as quick to judge someone as he used to be. Instead of simply seeing enemies as bad guys, he'd start to understand the reasons behind their actions. This could make him more empathetic but also more calculating in his approach to dealing with threats. Also, his normally boisterous nature would likely be toned down to avoid attracting unnecessary attention.
He would become more confident in his abilities. The Green Lantern ring gives its wielder a sense of power and purpose. Harry, who has always had self - doubts, would grow into a more self - assured person.