Perhaps the One Ring has some sort of connection to Voldemort. Harry, having the One Ring, finds that Voldemort is drawn to it because of its power. This could lead to a new battle where Harry not only has to face Voldemort but also has to decide what to do with the Ring. He might have to journey to find a way to destroy it, just like in the original 'Lord of the Rings' story.
Well, perhaps the One Ring is sent to Hogwarts as a mysterious artifact. Dumbledore, suspecting its great power and danger, enlists Harry to investigate. Harry, being the hero he is, soon realizes that the ring has a will of its own. He has to face the temptation of the ring while also dealing with the ongoing threat of Death Eaters, as the two evils start to intertwine in unexpected ways.
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.
Sauron, even in the context of this fanfiction crossover, could be an antagonist. His influence could reach the wizarding world through the One Ring. He might try to manipulate Harry or those around him to get the Ring back.
Hermione would be extremely worried. She'd start researching right away, trying to find out all she could about the One Ring. She might try to find spells to contain or protect against its power. As for Voldemort, he would see the One Ring as a tool to gain more power. He would likely be overconfident in his ability to control it, not realizing that the ring could potentially control him instead.
A great plot could be that the ring is a portal - creating device. When activated, it opens portals to different parts of the wizarding world and even some unknown magical realms. A group of dark wizards is after the ring to use it for their evil plans. Harry and his friends are on a race against time to protect the ring and close the portals that the dark wizards have already opened, all while learning about the origin and true power of the ring.
One possible plot could be that the Potter ring has some sort of ancient magic. Harry discovers it and when Daphne gets involved, they find out that the ring is tied to a prophecy. Together, they embark on a journey to unlock the secrets of the ring, facing various magical creatures and dark wizards along the way.
One possible plot could be that Harry discovers he has the Rinnegan during his time at Hogwarts. He initially has no idea how to control it, but as he learns, he starts using it to his advantage in his battles against Voldemort. Maybe he can use the Rinnegan's power to see the true nature of dark magic spells and counter them more effectively.
In this fanfiction, Harry might have the gun as a gift from a mysterious figure. The gun could have special powers like it can only be fired by him and the bullets can penetrate any protective spell. This would lead to a whole new set of adventures as he tries to figure out the origin and purpose of this unique weapon.
One possible plot could be that Harry's daughter discovers she has magical powers just like her father. She might struggle at first to control them and face some challenges at Hogwarts, but with the help of her father's wisdom and her own determination, she overcomes difficulties and becomes a great witch.
Well, it could be about Harry's adventures in managing a large family. Maybe each wife has a different personality and they all bring unique elements to his life. For example, one wife could be really into magic research and help Harry in his magical quests, while another might be more focused on family traditions and social events in the wizarding world.