Well, in such a fanfiction, Naruto might be really confused at first. The One Ring has its own dark power and lore from Middle - earth, while Naruto is from the ninja world. Maybe Naruto would think it's some kind of super - powerful ninja tool at first. He might try to use his chakra on it, not realizing the corrupting influence it could have. And his friends like Sasuke and Sakura would be very suspicious of this strange new item Naruto has found.
One possibility is that Naruto would try to incorporate the ring into his ninja gear. He's always looking for ways to get stronger. But the ring's power is not like normal ninja power. It could start to corrupt him slowly. For example, he might become more obsessed with power and less concerned about his friends' feelings.
Smeagol's sad story is about his transformation. He was originally a somewhat innocent creature. But when he got the Ring, his life changed. He killed his friend Deagol to keep the Ring for himself. This act of greed started his downward spiral. He was shunned by his people and had to live in the shadows, constantly in a state of paranoia and sadness as the Ring consumed his soul.
Well, if Naruto finds a Lantern Ring, he might initially be confused. He's from a world of ninjas and chakra, not the DC Universe's power rings. But being Naruto, he'd likely adapt quickly. Maybe he'd use the ring's power to enhance his ninjutsu, like making his Rasengan even more powerful. He could also use it to travel faster between villages, kind of like how Green Lanterns can fly across galaxies.
Well, perhaps Harry uses his magic to sense the One Ring's power. He might initially mistake it for a dark magical artifact from his own world. Then, he could start on a journey to figure out what this strange ring is, all while facing challenges from both the wizarding world (like Voldemort's followers thinking he has a new powerful weapon) and from Middle - earth forces that are also after the ring.
One possible plotline could be Harry's initial confusion when he stumbles upon the One Ring. He might wonder about its strange power and how it seems to call to him in a way different from magic he's used to.
I recommend to you the novel "The Road to Cultivating a Protagonist". The protagonist picked up a ring and obtained a special ability from it, opening the path of life to become a protagonist. I hope you like my recommendation. Muah ~
The key event was finding the One Ring. After that, his slow transformation into Gollum was significant. Also, his encounter with Bilbo Baggins when Bilbo took the Ring from him was important.