Well, in a Naruto in a Lord of the Rings Harem Fanfiction, the story could start with Naruto being mysteriously transported to Middle - earth. Since he's used to fighting and protecting in his own world, he quickly gets involved in the conflicts there. As for the harem part, he might encounter Elven maidens who are intrigued by his strange powers and his unwavering determination. The harem could also include some strong human women who see Naruto as a powerful ally. They would all bond over their shared goals of protecting Middle - earth from the dark forces, with Naruto's ninja skills and positive attitude influencing them all.
Arwen could be a potential member. She is a beautiful and strong - willed Elf, and Naruto's different - world charm might attract her. Eowyn could also be in the harem. She is a fearless warrior, and Naruto's equally brave nature could make them connect. And perhaps Galadriel, with her wisdom and power, would be intrigued by Naruto and his unique abilities, so she could be part of the harem as well.
One way it could work is by having Naruto characters in Middle - earth. For example, Naruto with his shadow clone jutsu could be a great asset in the battles against Sauron's forces. He could create clones to confuse the orcs and trolls. Meanwhile, characters from 'Lord of the Rings' could learn from Naruto's ninja skills. Frodo might pick up some stealth techniques from Naruto's training.
Aragorn could be a great choice. He already has a heroic and noble presence. In a harem fanfiction, he could attract various female characters from different regions of Middle - earth. His skills as a warrior and leader would make him an appealing focus for a harem story.
Well, Naruto would likely have to adapt to the different power system in One Piece. He could use his chakra to enhance his physical abilities in battles at sea. Maybe he starts as a lone bounty hunter but then gets drawn into the complex politics of the One Piece world. He could end up having to choose sides between different pirate crews or the World Government, all while trying to earn bounties on dangerous outlaws.
His character could become more complex. With the power of all lantern rings, Naruto would face new moral dilemmas. For example, the power of the Red Lantern ring which is based on rage might conflict with his usual positive - thinking self. He'd have to learn to control and balance all these different emotional - based powers.
Well, in a Young Justice fanfiction with Luffy, perhaps he could be introduced as a new recruit or a mysterious outsider. His presence would surely shake things up. Maybe he'd form an unlikely friendship with a character like Robin, who also has a complex past. And his goal of finding the One Piece could somehow tie into the overarching plot of Young Justice, like there could be a powerful artifact related to the One Piece hidden in the Young Justice world.
Well, it can change the whole course of events. For example, if a character travels back in time and warns Frodo about a particular danger he'll face, it could lead to a completely different outcome for the quest. Maybe Frodo would be better prepared and not get as injured or lost along the way.
The characters could interact in combat. For instance, Legolas' archery skills could be compared and contrasted with Naruto's ranged attacks using shurikens. They might train together and learn new techniques from each other.
Well, it could be about Juubi Naruto being transferred to the Highschool DxD world. Maybe he'd use his unique ninja skills to stand out among the devils and angels there. And with the harem aspect, he might attract the attention of various female characters from both universes.
A simple way would be to have a character from Prototype enter Middle - earth. They could bring their unique abilities, like super strength or shape - shifting, and use them against Sauron's forces. For instance, if Alex Mercer from Prototype was in Middle - earth, he could easily take on orcs and trolls in combat.