His character would become more powerful. The devil fruit power would add a new dimension to him.
Harry's character would change significantly if he ate a devil fruit in fanfiction. Firstly, his sense of self would be altered as he now has a power that is not part of his wizarding heritage. He would have to explore and understand this new power source. His relationships with his friends might also be affected. Some might be jealous, while others would be in awe. His approach to challenges would be different too. Instead of relying solely on magic, he'd have to incorporate his devil fruit powers, which would require a new way of thinking and strategizing. This would make him more versatile and complex as a character.
Well, if Harry ate a devil fruit in fanfiction, he might gain some extraordinary powers. For example, if it was a Logia - type devil fruit, he could transform into an element like fire or water. This would completely change his abilities and how he interacts with the world around him. He could use these new powers to fight against his enemies in a whole new way.
If Harry Potter ate a devil fruit in fanfiction, his identity would be more complex. He would no longer be just a wizard. He would be a wizard with the extraordinary powers of a devil fruit. His battles would be different. He could use his devil fruit power to surprise his enemies. For instance, if he had a devil fruit that allowed him to turn invisible, he could use it in combination with his disillusionment charm for an even more effective stealth approach. His life would be filled with new adventures as he explored the limits of his combined powers and tried to keep them a secret from those who might misuse this knowledge.
If Harry Potter ate a devil fruit, it would depend on the type. If it was a Paramecia type like the Gomu Gomu no Mi (Rubber - Rubber Fruit), his body would become rubbery. This would be quite interesting as he could stretch his limbs to reach far - off places or dodge attacks in a very unique way. He could also use his rubber body to absorb impacts from spells, adding a new dimension to his defense. It would be a really cool twist in the Harry Potter universe, mixing the magic from his world with the powers from the One Piece world of devil fruits.
His relationship with Sasuke might change. Sasuke is used to Naruto's regular abilities. But if Naruto had devil fruit powers, Sasuke might view him as an even greater rival or, in some cases, a potential threat. He could also be more intrigued by Naruto's new powers and be more likely to team up with him to face stronger enemies.
Naruto's character would develop in many ways. He might become more confident with the new powers from the Logia Devil Fruit. Since these powers are often very strong, he could feel more capable of protecting his village and friends. For example, if he had a lightning - Logia fruit, he could use it to defend against stronger enemies more effectively.
If Naruto found a devil fruit, it would open up a whole new world of possibilities for his adventures. He could travel to different lands in search of more knowledge about the devil fruit. Maybe he'd encounter other characters from different fictional universes who are also interested in devil fruits. His understanding of power and the world around him would expand. He'd no longer be just a ninja from the Hidden Leaf, but someone with a power that bridges different fictional concepts. This could lead to him becoming a sort of ambassador between the Naruto world and the world of One Piece - like elements introduced by the devil fruit.
In this fanfiction, Naruto's relationships would experience significant shifts. With his friends, they would initially be curious and a bit envious of his new power. However, as time goes on, they would learn to work with it. His relationship with the village elders might change too. They would likely be more cautious about Naruto, fearing the potential destruction that could come with his new, powerful ability. But Naruto, being Naruto, would strive to prove that he can use the Flame - Flame Fruit's power for the good of the village and its people, thus gradually earning their trust back and strengthening his bonds with them in the process.
If Naruto ate a devil fruit, he would gain some amazing new powers. For example, if it was a Logia type like the Mera Mera no Mi, he could turn into fire and use fire - based attacks in addition to his existing ninja skills. This would make him even more formidable in battles.
His fighting style would become more diverse. If he got a devil fruit, say the Ope Ope no Mi (Operation - Operation Fruit), he could create rooms and manipulate objects within those rooms. This would be a huge departure from his normal ninja attacks. He could trap enemies in these rooms and then use his kunai and shuriken skills within the confined space to defeat them.
His fighting style would become more diverse. If it was a Paramecia devil fruit, say the Gomu Gomu no Mi, he could stretch his limbs like Luffy. This would add a whole new dimension to his close - combat skills, allowing him to reach enemies from a distance and perform acrobatic attacks that his normal ninja training might not have included.