In a fanfiction where Naruto destroys Marineford, it could be due to his overpowered jutsu. Maybe he uses his Rasengan in a super - enhanced form that creates a massive explosion, leveling the Marineford. Another possibility is that he uses his Sage Mode to outmaneuver all the opponents there and then unleash a devastating attack.
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.
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.
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.
The other pirates would be inspired. For example, the Whitebeard pirates, who were already fighting hard, would see Luffy's Gear 5 power and get a new boost of morale. They might fight more aggressively, believing that they now have a better chance of winning. As for the Marines, they would be in shock and fear. The lower - ranked Marines would be terrified of this new form of Luffy, while the top officers like Sengoku would have to quickly re - evaluate their battle plans.
Well, in this fanfiction, Luffy could interact with the Marines in a more diplomatic way. Since he has the advantage of time travel, he might understand the reasons behind the Marines' actions better. So, he could try to negotiate or make deals with some of the more reasonable Marines. He could offer to help them with other threats in the One Piece world in exchange for them leaving his friends alone at Marineford.
Luffy and Ace's interaction is always key. In fanfiction, it could be that Ace reveals a secret to Luffy right before the final battle that gives Luffy newfound strength. Another great interaction could be between Luffy and Garp. Garp might be conflicted between his loyalty to the Marines and his love for his grandsons, and this inner turmoil could lead to some really emotional and tense moments when he interacts with Luffy at Marineford.
One consequence would be a major shift in the power balance in the One Piece world. The Marines would be severely weakened, and pirates might become more bold. Another consequence could be that Naruto would become a huge target for both the remaining Marines and other powerful forces in the One Piece world.
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 could be that Gear 5 Luffy arrives at Marineford during the big battle. He might use his newfound powers to turn the tides of the fight. For example, he could use his rubbery abilities in even more extreme ways, like stretching to deflect cannonballs aimed at his allies and then bouncing them back at the enemy ships. His presence would shock both the Marines and the pirates. He could also engage in a one - on - one fight with some of the top Marine officers in a more comical yet powerful way, as Gear 5 gives him a more carefree and powerful fighting style.