Well, perhaps Harry would use magic to stop the iceberg from hitting the Titanic. He could cast a spell to make the iceberg disappear or move it out of the ship's path.
In this fanfiction, Neville could also play a role. He has grown into a brave and capable wizard. He might use his skills with plants to create some sort of magical plants that could help, like plants that can grow quickly to block the path of the iceberg or to repair any damage to the ship. And Luna could be there with her unique perspective, perhaps she could sense the danger in a different way and help Harry in his mission to save the Titanic.
In some fanfictions, Harry might use his magic skills. For example, he could use spells to protect Naruto from a powerful enemy. Maybe he casts a shield charm to block an attack that Naruto couldn't avoid on his own.
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.
Harry would be quite surprised at first. He'd be thrown into a world without magic, yet full of strong emotions and drama. He might feel a bit out of place, but as he gets into the story, he'd start to understand the human nature in it. He could admire the courage of the characters, like how they faced the disaster. And he might also be a bit confused by some of the muggle concepts like the class system on the ship.
One unique aspect is the combination of two very different universes. You have the magical world of Harry Potter with spells and wizards, and then the historical and romantic setting of the Titanic. It's like mixing fantasy with a real - life tragedy.
It could be some dark wizards who want to use the centaur's parts for potions. They might be following some ancient, dark magic recipe that requires centaur hair or hooves. So they hunt down the centaur, but Harry gets in their way.
In this fanfiction, perhaps the centaur is in a situation where it's about to be sacrificed in some dark ritual. Harry discovers this and races against time to stop it. He calls upon his friends Hermione and Ron for help. Hermione uses her vast knowledge of magic to figure out how to break the dark magic circle, while Ron provides some much - needed comic relief during the tense situation. Harry, of course, is the one who ultimately uses his powerful Patronus charm to dispel the dark forces and save the centaur.
Zoe could be a new student at Hogwarts who gets into trouble. Maybe she's a first - year who wandered into the Forbidden Forest by accident and Harry has to save her from the dangerous creatures there.