A theme centered around the development of friendships among different houses in Hogwarts is also very suitable. Such as a story where students from Gryffindor, Hufflepuff, Ravenclaw, and Slytherin come together to solve a mystery that affects the whole school. This can show the unity and diversity within the Hogwarts community, which is an important aspect of the 'Harry Potter' world.
One common theme is the further exploration of character relationships. For example, delving deeper into the friendship between Harry, Ron, and Hermione. This could involve creating new adventures that test and strengthen their bond.
Another one is 'The Potter's Apprentice' which imagines an alternative storyline where Harry has a different kind of training. It's well - written and has a lot of interesting twists on the original plot. These fanfics are great because they add to the richness of the Harry Potter universe without relying on inappropriate content.
Some fanfics revolve around the relationships in a more platonic and positive way. Like the friendships between different houses getting stronger. It could show how students from Gryffindor, Hufflepuff, Ravenclaw and Slytherin come together to solve a problem that affects the whole wizarding world, rather than just their own houses.
There are many great and appropriate Harry Potter fanfics. For example, some focus on the adventures of the characters outside of the main story in Hogwarts, like exploring new magical creatures in the Forbidden Forest. Another type might be about the friendships between the characters growing stronger during their holidays. There are also ones that delve into the backstories of minor characters, which can be really interesting.
There are many great 'Harry Potter' fanfics. For example, some focus on the backstories of minor characters like Neville Longbottom. They might explore how he overcame his insecurities before Hogwarts. Another type could be about the Marauders' era, showing the friendship between James Potter, Sirius Black, Remus Lupin, and Peter Pettigrew. These fanfics add depth to the already rich 'Harry Potter' universe without going into inappropriate territory.
Rather than seeking such inappropriate fanfics, if you want to incorporate educational elements into the Harry Potter world, you could consider fanfics that deal with the characters learning about different cultures within the wizarding world (like how different magical communities handle family values), or about moral values and ethics which are important aspects of growing up, similar to what the characters face in the original books when dealing with the threat of Voldemort.
Another one is 'The Time - Twisted Trio'. In this fanfic, they accidentally travel back in time and have to deal with the past versions of themselves and their friends. It's really interesting to see how they handle the situation while still maintaining their core characters.
One popular theme is the 'what - if' scenarios. For example, what if Voldemort had never existed? How would the wizarding world be different? Another theme is the exploration of different magical creatures in more depth. Fanfic writers often create new adventures involving creatures like hippogriffs or thestrals.
One appropriate theme is to rewrite certain parts of the story from a different character's perspective. For instance, seeing the events of the Triwizard Tournament from Cedric Diggory's point of view. Or exploring how the wizarding world copes with the aftermath of the Battle of Hogwarts in different regions that were not covered in the original books.
One appropriate theme could be exploring the post - Hogwarts lives of the characters. For example, how they use their magic in the Muggle world or how they contribute to the wizarding society in new ways.