A more complex plot could be a magical threat that affects both the Harry Potter world and the world of OHSHC. The characters from both universes have to team up. The Host Club members use their charm and unique skills, like Kyoya's intelligence in strategizing, along with the magical powers of Harry and his friends to defeat the threat. For example, the Dementors could start appearing in the OHSHC world, and they need to find a way to combat them using both magic and the Host Club's emotional support skills.
One idea could be that Harry Potter, somehow transported to the Ouran High School Host Club's world, has to hide his wizarding abilities while getting involved in the club's antics. Maybe he uses his magic subtly to help the club members in their personal problems, like using a spell to make Tamaki less clumsy during their hosting sessions.
A great plot for a Potter Manor fanfiction could involve a mystery that surrounds the manor. For instance, strange noises at night lead Harry to uncover a long - forgotten chamber. It could also be about Harry restoring the manor to its former glory, perhaps with the help of Hermione's research on ancient magic used in the construction of such manors.
One interesting plot idea could be exploring what would happen if Harry had a different upbringing, like being raised by the Malfoys. It would completely change his view of the wizarding world and his relationships. Another idea might be a time - travel fanfic where Harry goes back to the Marauders' era and interacts with his parents and their friends. This could lead to him preventing certain tragedies or changing the future in unexpected ways. And then there's the concept of a fanfic where the roles are reversed, and Voldemort is the one trying to protect the wizarding world from a greater evil, with Harry being the main antagonist.
Romance is often explored as well. There could be pairings like Draco and Tamaki, which brings together the rather different personalities from the two series. The fanfictions play with the idea of how these characters from different backgrounds could fall in love and what their relationships would be like.
One idea could be Harry Potter using his wizard skills in a boxing ring in a unique way. For example, he might use a levitation charm to dodge punches or use a stunning spell on his opponent's gloves to make them heavier. Another could be a story where the wizarding world has its own boxing league and Harry has to compete against other magical beings like werewolves or giants in the ring.
An enchanter in a fanfiction could create a spell that allows them to communicate with portraits in a way that has never been done before. For example, they could get advice from portraits of long - dead headmasters on how to deal with the current political situation in the wizarding world. Another plot might be that an enchanter is able to enchant the Sorting Hat to sort students based on their future potential rather than their current characteristics. This could lead to some students being placed in houses that they never expected. And finally, an enchanter could be working on a spell to make the Hogwarts Express invisible during its journey, but things go wrong and the train starts to disappear and reappear at random intervals, causing panic among the students.
One idea could be that Amara is a new student at Hogwarts with a special power to communicate with magical creatures in a way no one else can. Harry discovers this and they team up to solve a mystery involving a group of sickly unicorns in the Forbidden Forest.
One idea could be a wedding between a wizard from Gryffindor and a witch from Slytherin, which could cause a stir among the Hogwarts alumni. They might have to overcome the old prejudices of their houses. Another could be a wedding set during a time of peace after the battle of Hogwarts, with characters like Harry and Ginny as guests, and the wedding could incorporate a lot of traditional wizarding wedding elements like flying doves made of light magic.
One idea could be that Lelouch, with his strategic mind, somehow gets transported to the Harry Potter world. He could use his Geass ability in a very different way, like influencing Death Eaters to turn against Voldemort. Another could be Harry Potter and Lelouch teaming up to fight a common enemy that has elements of both their worlds, perhaps a dark wizard who has also mastered some form of mind - control magic similar to Geass.
A plot could involve Belphegor disguising himself as a new teacher at Hogwarts. He starts to influence the students in a negative way, spreading laziness and chaos. Harry Potter senses something is wrong and with the help of Hermione's research and Ron's loyalty, they discover the true identity of the 'teacher' and try to stop his evil plans.
One idea could be that Belmont is a long - lost relative of Harry Potter who shows up at Hogwarts with some unique magical abilities that even the professors are in awe of. He could help Harry in his fight against Voldemort in unexpected ways.