One possibility is that Harry is escaping from some danger in the wizarding world. He boards the ship to get as far away as possible. While on the ship, he discovers that the ship has its own secrets and magic. He gets involved in the ship's internal affairs, like helping the crew deal with a curse that has been plaguing them.
Maybe Harry Potter steals a ship to escape from some dark wizards who are chasing him. He uses his magic skills to sail the ship stealthily and heads towards a hidden island where he hopes to find a powerful magical artifact to defeat the dark forces.
The plot could involve Harry building the ship with the help of his friends. They could all contribute their skills. For example, Hermione could use her vast knowledge of magic theory to ensure the ship's construction is perfect, while Ron could offer his practical skills. They might be building the ship to escape from some new dark force that has emerged in the wizarding world. Harry's ship would then be their means of getting away and finding a new place to start over. It could also be a ship that has special magical properties, like being able to fly or travel through time.
Well, perhaps Harry Potter uses his magic to gather materials from all over the wizarding world. He might use spells like 'accio' to bring in rare woods and magical metals. Then, with the help of his friends like Hermione, who could research the best construction spells, and Ron, who provides the brute force when needed, they start building the city - ship. It could be a floating city with different areas for Hogwarts - like classrooms, places for Quidditch, and areas for magical creatures.
Well, it could be about Sakura and Itachi meeting secretly in a forest. They share their hidden thoughts and feelings, perhaps about the chaos in their ninja world. And they gradually form a bond that no one else is aware of.
One possible plot could be that the RWBY characters are recruited to join a space ship fleet on a mission to save a distant planet from an ancient evil. They have to adapt to the new environment of space and the technology of the fleet while still using their unique combat skills.
One possible plot could be that Harry discovers his passion for cooking in a magical kitchen at Hogwarts. He starts experimenting with different magical ingredients and creates unique dishes that even the house - elves are impressed by.
One possible plot could be that Harry, after a difficult battle in the wizarding world, stumbles upon Deadpool's adventures in the muggle world. He becomes obsessed with Deadpool's carefree yet effective way of fighting. So, he starts training himself in a similar style and uses it to outwit his enemies in Hogwarts.
The plot could involve Harry arriving in Skyrim and being mistaken for a powerful mage. He gets caught up in the political intrigue of the different factions in Skyrim. For instance, the Stormcloaks might try to recruit him because they think his magic can give them an advantage in the civil war. Meanwhile, he's also trying to find a way back to his own world.
Maybe it's about Harry being wrongly accused and his fight to prove his innocence while in jail. He could be making friends with some unlikely characters in the jail who help him in his quest.
Maybe Harry somehow gets transformed into a fawn or has a connection with a fawn. It could be a magical adventure where he has to navigate the world as a fawn or protect the fawn from some sort of danger.