Maybe a card magician who travels through different wizarding schools in the Harry Potter universe using their card magic as a form of communication and as a tool to solve mysteries. For example, they could use cards to find hidden passages or secrets in Hogwarts, Beauxbatons, and Durmstrang. The cards might have special symbols that only the magician can understand and that are related to the history and magic of each school.
One idea could be a young wizard who discovers they have a unique talent for card magic within the wizarding world. They use their card tricks to outwit dark wizards, like making cards transform into protective spells or creatures to fend off attacks.
One idea could be a young wizard who discovers a rare deck of magic cards that have the power to transport him to different parts of the wizarding world. He could use these cards to solve mysteries and help his friends.
One idea could be creating a new type of card that has a special power related to time - like being able to go back in time during a game. Another could be a story where a character discovers a rare and powerful card that was thought to be lost forever. And a third idea might be a tournament where the cards have been enchanted in strange ways, causing unexpected things to happen during the matches.
One idea could be a wizard using card magic to solve a mystery at Hogwarts. Maybe the cards hold clues that only the protagonist can decipher through their knowledge of card magic.
Well, you could have a fanfic where Voldemort uses DND - style dark magic to open portals to other dimensions. The Order of the Phoenix has to quickly learn DND - style combat and magic rules to fight off the new threats that come through these portals. Harry could be sent on a special mission to find a DND - style mage who can teach them the counter - spells. Meanwhile, the Death Eaters are also trying to master this new form of magic for their own evil purposes. This would create a really exciting and unique story.
Perhaps a plot where the protagonist can choose to either side with the Ministry of Magic during a time of political unrest within the wizarding world or join a rebel group. This would involve different magical battles and moral dilemmas depending on the choice. In the 'harry potter cyoa fanfic', this could show different aspects of the wizarding society that we don't often see in the original books.
A cool plot for a Harry Potter Twilight fanfic could be a competition. The wizards from Harry Potter and the vampires and werewolves from Twilight compete in a series of challenges. These challenges could test both magic and the unique abilities of the Twilight characters. Or perhaps a love triangle between a Harry Potter character, a Twilight vampire, and a Twilight werewolf. It would be interesting to see how the different cultures and powers interact in matters of the heart.
Another plot could focus on the lives of the secondary characters from the original series. For example, Neville could be the head of Herbology at Hogwarts and discovers a new, dangerous plant that has some sort of connection to an ancient magic. The 'carry on fanfic' could then be about how he and his students deal with it, with some cameos from the main characters.
One idea could be that a dragon escapes from Gringotts and Harry has to use his skills to track it down. Maybe the dragon has a special connection to a powerful dark magic item that Voldemort was after.
One idea could be that Voldemort somehow enters the Runescape world to seek more power. Harry and his friends follow him there to stop him. They have to learn the rules of Runescape quickly to be able to fight Voldemort. Another idea is that a Runescape wizard discovers a portal to the Harry Potter world and brings some of the unique items from Runescape, like special runes, which causes a stir in the wizarding world.
A great plot for a Harry Potter academy fanfic might be a time - travel scenario. A group of students accidentally travel back in time to the founding days of Hogwarts. They have to navigate the different rules and attitudes of that era while also trying not to change history too much. Or perhaps there's a plot where a student is wrongly accused of a major crime at the academy and has to prove their innocence. They'll need to use their wits and the help of their friends to find the real culprit.