One interesting plotline could be Harry dealing with the aftermath of the war in Hogwarts. He might be trying to heal the school and its students from the trauma. Another could be his relationship with Ginny evolving further as they face new challenges together in their final year.
In some fanfictions, the 8th year could focus on Harry exploring more of the secrets within Hogwarts. Maybe he discovers new spells or hidden rooms that were previously unknown. This could lead to adventures with his friends, like Ron and Hermione, as they all strive to make the wizarding world a better place post - war.
One interesting plotline could be exploring more of Snape's inner turmoil during Harry's 6th year. Maybe showing his secret efforts to protect Harry while still maintaining his cover among the Death Eaters.
One interesting plotline could be Harry's struggle with his new role as a leader in Dumbledore's Army. He has to deal with the pressure of teaching his peers and also keeping the group a secret from Umbridge.
A possible plotline could be that Hogwarts itself becomes a sort of magical battleground earlier than expected. The Death Eaters try to take over the school completely, and the students and remaining teachers have to fight back in a sort of guerilla warfare within the castle walls. This would change the whole dynamic of the seventh year, with classes being interrupted and students having to use their magic in real - life combat situations.
One interesting plotline could be a deeper exploration of the Triwizard Tournament tasks from a different perspective. Maybe showing the behind - the - scenes preparations by the champions that we didn't see in the original book. Another could be a new relationship developing between characters, like a friendship between a Hogwarts student and a Durmstrang student that impacts the events of the tournament.
In many Harry Potter 8th year fanfic plotlines, the exploration of the wizarding world outside of Hogwarts becomes a major focus. Harry and his friends could be traveling to different wizarding communities, learning about their cultures and magic. They might encounter new magical creatures and have to figure out how to interact with them. There could also be a mystery involving a powerful, ancient magic that is somehow related to their 8th year at Hogwarts, and they have to solve it to keep the wizarding world safe.
In some fanfictions, there could be a plotline where Harry and Hermione start to realize their feelings for each other in a different way during their 6th year. They've been through so much together, and this year could be the turning point where their relationship evolves from just friendship. They might have more private moments, sharing their fears and hopes, and this newfound closeness could lead to a whole new dynamic in their relationship.
Another interesting plot could be that Harry's connection to Voldemort causes some strange magical disruptions during the Triwizard Tournament. These disruptions seem like accidents at first, but Harry gradually realizes they are being caused by his own dark - side related powers that are being awakened in his fourth year.
In some fanfiction, there are plotlines where the Death Eaters have a different strategy. Instead of just following Voldemort blindly, they start to have their own power plays. This could lead to a more complex battle between the good and the bad. Also, there could be a plot where Harry has to deal with a new magical ability that he discovers during year 7, which changes the whole dynamic of the fight against Voldemort.
One interesting plotline could be Harry secretly learning advanced magic on his own to better prepare for the coming battles. He might discover an old, forgotten spellbook in the Room of Requirement.
A common plotline is the deepening of relationships. For example, Harry might further develop his friendship with Draco. They could start to understand each other better, realizing that they were both products of their upbringing. Also, Hermione could take on more leadership roles in the school, like starting new study groups or magical research projects, which would be really exciting to read about in fanfiction.