If Naruto arrives at Marineford, it would be a chaotic and interesting scenario. Naruto's powerful jutsu like Rasengan and his ability to summon toads could change the balance of power. He might try to stop the fighting between the pirates and the marines, seeing the senseless destruction. His sense of justice and never - give - up attitude could inspire some of the characters there.
Yes, there might be. The 'Harry Potter' and 'One Piece' (where Marineford is from) fanfic communities are quite large and creative. There could be a crossover where Harry Potter somehow saves Ace at Marineford. You can check fanfic platforms like Archive of Our Own or FanFiction.net to see if such a story exists.
One possible plot development could be that his death shatters the Straw Hat crew. They might disband in grief, each going their own way. Zoro could become consumed with revenge, vowing to take on the Marines who were responsible.
Naruto would be very curious. He'd want to understand what's going on. Once he figures out that there's a big battle between different factions, he'd try to find a peaceful solution. He might start by talking to the leaders, using his charm and persuasion skills. If that doesn't work, he'd use his ninja powers to protect the innocent. He's not one to just stand by when there's injustice.
Well, 'OP' in the context of this 'Fury Tries to Kidnap OP Harry Potter Fanfiction' could be the main character that Fury is targeting because of their special powers. Maybe it's a new character created by the author with unique magical abilities that Fury, for some reason, wants to get his hands on. It could be someone with a combination of different magical skills from the original Harry Potter universe, like being able to perform extremely powerful spells without a wand or having the ability to control all types of magical creatures.
Nami would probably be heartbroken. She has been with Luffy through so much and his death would leave her feeling lost and alone. She might even lose her will to continue sailing at first.
Well, Harry Potter might be magically transported to the 'One Piece' world just in time to save Ace. He could use his Patronus charm to fend off the attackers at Marineford. Since his Patronus is a powerful form of positive magic, it could be strong enough to hold off the Marines for a while. He might also use his knowledge of potions to heal Ace if he's already injured. And perhaps he forms an alliance with Luffy and the Straw Hats to help them get out of the dangerous situation at Marineford.
Well, in the fanfiction, Gear 4 Luffy might have had some new and unexpected interactions. Maybe he could have teamed up with some other pirates in a different way. Since he was in such a powerful form, he could have inspired more of the pirates to fight back more bravely against the Marines. And his presence in Gear 4 could have also affected the admirals' strategies, making them more cautious or forcing them to use their more powerful techniques earlier.
It would likely make the storyline more exciting. Gear 4 Luffy is extremely powerful, so his presence in Marineford would change the power dynamics. He could defeat more enemies quickly.