The wizard Gandalf would be an obvious character for Harry to interact with. They are both wizards, though from different worlds. They could share their knowledge of magic, and Gandalf could guide Harry in the ways of Middle Earth while Harry could introduce some new magical concepts to Gandalf.
Well, he might be really confused at first. Middle Earth has its own unique magic system and races. Harry, with his Hogwarts - trained magic, would have to adapt. He could probably make friends with some of the elves, like Legolas, as they both have a sense of honor and skill in archery. And his encounter with Gandalf would be really interesting, as they are both powerful wizards in their own ways.
One possible plot could be that Naruto is mistaken for a powerful wizard when he arrives in Middle - earth. He then has to prove himself to the various races there. Along the way, he uses his rasengan to blast through orc hordes and his shadow clone jutsu to create distractions during battles. He also learns about the magic of Middle - earth and tries to combine it with his own ninja powers.
He would probably befriend the hobbits. The hobbits are friendly and curious, and Naruto's energetic and kind - hearted nature would attract them. They could learn a lot from each other, like the hobbits could teach Naruto about their simple but fulfilling way of life.
Well, he might be really confused at first. Middle Earth has its own rules, magic, and races. Percy, with his water powers, could have some interesting interactions with the rivers and seas in Middle Earth. Maybe he'd help the Fellowship in some way, like using his powers to create distractions during battles or to cross dangerous water areas.
Harry's magic is more about instant spells using his wand. In Middle Earth, magic seems more subtle and connected to the land. But Harry's powerful offensive spells like the Stunning Spell could be quite effective. His ability to fly on a broomstick would be a unique advantage. However, the wizards in Middle Earth, like Saruman and Gandalf, seem to have a more profound understanding of the deeper magic of the world.
Fanfiction in the Middle Earth Shadow of War universe can offer unique and exciting stories. One could write about a new hero emerging in Middle - earth, perhaps a ranger from a far - flung region who discovers a hidden power that could change the fate of the war against Sauron. This new character could form alliances with both familiar faces like Aragorn and new, original characters created for the fanfic.
He might meet a hobbit first. Hobbits are curious and friendly, and they live in areas that are likely to be where Percy would first arrive. Maybe he'd stumble upon Bilbo or Frodo's place. The hobbits would be really surprised by Percy, but they'd also be very hospitable.
Well, he might use his magic in unexpected ways in Middle - earth. Maybe he'd befriend the hobbits and use his spells to protect them from orcs. For example, he could create protective shields around the Shire.