One interesting fanfiction could be about his first time making real friends at Hogwarts. He might have some initial awkwardness but then quickly forms strong bonds with Ron and Hermione. For example, in a fanfic, it could show how he was nervous about sharing a dormitory with strangers at first but then realized they were all in the same boat.
Another fanfiction could focus on his first time in a Hogwarts class. Maybe it's his first Potions class with Snape. The fanfic could detail his anticipation, the strict atmosphere in the classroom, and how he coped with Snape's initial dislike for him. It could also show his determination to learn and prove himself in the class.
One great fanfiction could be about James Potter's mischievous adventures at Hogwarts before he met Lily. Maybe it details his pranks with Sirius and Remus, and how those experiences shaped him into the person who would later fall in love with Lily. Another could focus on Lily's academic achievements and her friendships at Hogwarts, and how she dealt with the attention from James at first. There are also fanfictions that might explore their early days of getting to know each other through their shared love for Hogwarts and magic in general.
One interesting fanfiction could be about the founders' early days at Hogwarts. It might explore how they decided on the house traits and chose the locations for each house within the castle. For example, a story could show Salazar Slytherin's initial ideas for the Slytherin common room being more open but then changing his mind due to certain events or other founders' suggestions.
A great 'Harry Potter Lockdown Hogwarts' fanfiction idea is that the teachers have to find new teaching methods during lockdown. Professor McGonagall might use magic to create virtual classrooms where students can interact with magical creatures from afar. And Professor Snape could come up with a potion - making challenge that the students can do in their dormitories, and they submit their results for grading.
Another fanfic could be about Harry's first time flying on a broomstick during the flying lessons. It could show his natural talent emerging as he soars through the air, and how it was the start of his love for Quidditch.
One interesting fanfiction could be where the Hogwarts castle itself becomes sentient and tries to protect the students in ways that are not in the original books. For example, it might create secret passages or defenses against new threats.
One great fanfiction could be about Harry and Ginny's secret adventures in the Forbidden Forest during their Hogwarts years. They might discover a hidden magical creature that has been lost for centuries.
One great Harry Potter time travel fanfiction is 'The Time - Turner's New Purpose'. In it, Hermione discovers a hidden ability of the Time - Turner that allows for more complex time travel. It's full of adventure as she uses it to prevent a dark wizard from an earlier era from coming back to power. The character interactions are really well - written, especially between Hermione and the Marauders.
Another great story is Harry's first Quidditch match. He's a novice, but his natural talent on the broomstick shines through. He has to face the Slytherin team, which is quite intimidating, but he manages to catch the Golden Snitch and win the match for Gryffindor, which really cements his status as a hero among his housemates.
One great 'Harry Potter leaving Hogwarts' fanfiction could be 'The Next Chapter'. In this story, Harry leaves Hogwarts with a sense of both melancholy and excitement for the future. It delves into his new relationships outside the school walls.
One great post - Hogwarts Harry Potter fanfiction is 'The Changeling' which explores Harry's life as he deals with the after - effects of the war and tries to build a new magical world order. Another is 'The Unseen Potter' that focuses on Harry's secret adventures away from the public eye.