Another idea might be the crossover with historical settings. Picture Hogwarts in the middle of a medieval European kingdom. The contrast between the wizarding world and the historical context can lead to really engaging storylines, like how the wizards deal with the political and social structures of the time.
In 'harry potter multi compartment trunk fanfiction', it's possible that the compartments are enchanted in unique ways. For instance, one compartment could have an infinite space inside, where characters can store as many items as they like without worrying about running out of room. Some fanfictions might also explore the idea that the trunk's compartments are connected to the emotions or magical powers of the owner. So, if the owner is feeling angry, a particular compartment might open up that contains something related to that emotion, like a potion to calm down or a weapon to defend against threats.
Well, in 'harry potter multi pairing fanfiction', a great plot could be the development of a relationship between Sirius and Remus while Harry is in the middle of trying to understand his own feelings for Cho and Padma at the same time. It would add a layer of complexity as Harry looks up to Sirius and Remus, and their relationship might influence his views on love. Also, a plot where Fred and George have a friendly competition over the affections of Angelina and Alicia could be really fun. It would show their mischievous side in a new context of relationships.
One idea could be Harry forming a study group that gradually turns into a close - knit 'harem' of friends with different magical abilities. They could go on adventures outside of Hogwarts together, exploring hidden magical places and solving mysteries that the school staff doesn't even know about.
For 'rwby multi crossover fanfiction', a crossover with 'Fullmetal Alchemist' would be interesting. RWBY characters could interact with the alchemists and learn about alchemy. They might even find ways to combine their Semblances with alchemy. Also, a crossover with 'My Hero Academia' would be exciting. The RWBY heroes could train with the students at U.A. High and exchange combat techniques and strategies.
Another possibility is that Voldemort somehow discovers the world of Narnia and tries to conquer it. This would force the Narnian characters to team up with the Order of the Phoenix. Harry Potter and his friends could learn about the talking animals and different forms of magic in Narnia, while the Narnian heroes would see the power of wizardry. It could lead to a great adventure full of battles and new friendships.
A cool Harry Potter OC Crossover Fanfiction idea could be to have an OC crossover with the world of Middle - earth. Imagine an OC from Hogwarts traveling to Middle - earth and using their magic to help in the battles against Sauron. They could introduce wands and spells to the hobbits and elves. Also, a crossover with the world of Fairy Tail would be interesting. The OC could join the Fairy Tail guild and participate in their quests while also showing off the unique magic of the Harry Potter universe. And a crossover with the world of Howl's Moving Castle could be fun too. The OC could interact with Howl and Sophie and learn about their form of magic which is different from Hogwarts magic.
One idea could be a magical exchange program. Wizards from Hogwarts and Dragon Riders from Alagaƫsia meet and learn from each other's magical systems. Harry Potter characters could be fascinated by the bond between Eragon and his dragon Saphira, while Eragon might be intrigued by the variety of magic at Hogwarts like Transfiguration and Potions.
One idea could be having Harry Potter characters attend an anime - style magic school in Japan. For example, Harry could be a transfer student to a school where they teach magic in a very different way compared to Hogwarts, with elements like anime - inspired uniforms and more focus on martial arts - based magic.
Perhaps there could be a magical object in 'Harry Potter' that is somehow related to the werewolves in 'The Howling'. For example, a spell book that has the secrets to controlling werewolf transformations. The characters from both worlds could be on a quest to find this book and in the process, they learn more about each other's worlds and how magic works differently in each.
A great idea for 'harry potter and friends crossover fanfiction' is a crossover with 'Narnia'. The magical world of Narnia and Hogwarts have some similarities. Harry and his friends could enter Narnia through a magical portal in Hogwarts. They could help the Pevensie children in their battles against the White Witch. Another option is a crossover with 'The Chronicles of Prydain'. Harry and his friends could journey to Prydain and encounter the magical creatures and challenges there. And a crossover with 'Fantastic Beasts' but in a different way, like the main characters from 'Harry Potter' meet Newt's ancestors and have adventures with them.