Well, he might start breathing fire! Ghost peppers are extremely hot, and Harry's magic might not be able to prevent his mouth from feeling like it's on fire. His face would probably turn bright red, and he'd be gasping for water or some kind of cooling spell.
If Harry Potter were to eat a ghost pepper in a fanfiction, it could have a significant impact on his day. First, the pain would be immediate. His eyes might water profusely as his taste buds go into shock. He could accidentally cast spells due to the sudden jolt of pain. For example, he might turn a nearby object into ice in an attempt to cool his burning mouth. His relationship with food in the wizarding world might also change. He might be more cautious about trying new and strange magical foods after this experience.
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.
Well, if Harry Potter ate the Ope Ope no Mi in a fanfiction, he might gain the ability to create a 'room' and perform surgical - like operations. He could use this power in his battles against Voldemort. For example, he could isolate Voldemort in a 'room' and then use his magic to try and defeat him without harming others around.
Well, it's a very strange concept. Maybe in this fanfiction, the 'sucker' is some kind of magical candy that has a really unexpected effect on Harry Potter. For example, it could make him start speaking in a strange language or have some wacky magical abilities for a short time.
In such a fanfiction, Harry Potter as a ghost might have a very different perspective on the wizarding world. He could be able to pass through walls and observe things secretly. Maybe he would try to influence the living wizards in some mysterious ways, like guiding his friends to discover hidden secrets or solve mysteries that were left unsolved when he was alive.
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.
Well, if Harry Potter becomes a ghost in a crossover fanfiction, it would change the whole dynamic of the story. He would no longer be bound by the same physical limitations as a living wizard. For example, he could travel across different fictional universes more easily as a ghost. Maybe he'd end up in the world of Narnia and interact with the characters there. His presence as a ghost could also bring a sense of mystery and unease to the crossovers. He might be a guiding spirit for some characters, or a source of fear for others depending on how they perceive ghosts in their respective worlds.
In the fanfiction, if Harry eats the Gum - Gum Fruit, it could completely change his personality. He might become more carefree and adventurous, similar to how Luffy is. His relationships with other characters would also shift. For example, his friends might be both amazed and a bit worried about his new powers. And he would probably have to learn how to control his stretching abilities, which could lead to some humorous situations as he accidentally stretches too far or gets stuck in a strange position.
Most fans would be disgusted. They've grown up with the story of Harry Potter as a symbol of good, and this kind of fanfiction completely undermines that. It would be met with a lot of criticism and probably calls for it to be removed from any platforms where it might be posted. The fandom values the integrity of the original story, and this is a blatant violation of that.
His friends would probably be quite shocked at first. Ron might laugh hysterically while Hermione would be more concerned and try to find a spell to ease the pain.
He might also be a bit confused at times. Some fanfictions deviate a lot from the real events in his life. For example, if there's a fanfiction where he has a completely different upbringing, it would be strange for him to read about. He could also feel a sense of flattery that so many people are interested in his story and want to create their own versions of it.