What are some interesting plot ideas for a Harry Potter lost and found fanfic?

One idea could be Harry Potter arriving in Skyrim and using his magic to combat the dragons. Maybe he teams up with the local mages and they learn from each other's magical techniques.

One idea could be exploring what would happen if a new, mysterious student joined Hogwarts during the Triwizard Tournament. This student could have a hidden agenda related to the Dark Arts and start influencing the events of the tournament in unexpected ways.

One interesting plot idea could be Harry's return to Hogwarts as a teacher. He could pass on his unique experiences and knowledge to the new generation of students.

One idea could be a dragon that forms a bond with Harry and helps him in his battles against Voldemort. Maybe the dragon has some special powers that are crucial for Harry to win.

One idea could be Harry and his friends exploring new magical realms that were previously unknown. Maybe they discover a hidden school of magic that has a different approach to teaching spells.

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.

Well, a great plot for a Harry Potter mansion fanfic could be centered around a lost heirloom. The mansion was once owned by an important wizarding family, and a valuable heirloom has been lost within its many rooms and corridors. The characters embark on a quest to find it, facing various challenges like magical traps and puzzles. Also, the mansion could be a place where time behaves differently. People who enter might find themselves in different eras of the wizarding world, and they have to find their way back to the present while also uncovering the secrets of the mansion's past.

In some 'harry potter apocalypse fanfic' plots, there could be an invasion from another dimension full of dark and powerful creatures. This invasion could be the start of the apocalypse. Harry Potter and his allies would have to quickly learn about these new threats and find ways to defend the wizarding world. It might also involve a situation where the Ministry of Magic fails completely during the apocalypse, and it's up to the students and a few rogue wizards to save the day. They could discover new and hidden magics in the process of fighting for survival.

A possible plot is that there is a hidden chimera colony in the Forbidden Forest. Harry discovers it during one of his adventures. The chimeras there are different from the known ones, with some having the ability to communicate telepathically. Harry has to figure out how to interact with them and gain their trust, as they hold a key to an ancient magic that can defeat Voldemort.

Maybe the Dragonborn and Harry Potter team up. The Dragonborn teaches Harry about ancient magic that is similar to his Thu'um, and Harry teaches the Dragonborn about wizardry like Apparition. They could go on a quest to find a powerful magical artifact that is being sought by Voldemort and a powerful dragon in the fanfic world.