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 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 plot could be that Harry has premonitions about the Triwizard Tournament tasks before they happen. These premonitions are not clear at first, but as he gets closer to each task, he starts to understand them better. It adds an element of mystery and foreshadowing to the story.
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.
One great fanfiction idea could be Harry dealing with the Triwizard Tournament challenges in unique ways. Maybe he discovers a hidden power within himself that helps him out during the tasks, like a new form of magic he didn't know he had.
One interesting plotline could be Harry mastering new and powerful magic that was not explored in the original books. For example, he might discover a long - lost spellcasting technique. Another could be his relationships with other characters evolving in different ways, like a deeper friendship with Neville or a different kind of mentorship with McGonagall.
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 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.
Obviously, Harry Potter himself is still very popular. Fanfiction often focuses on his growth and his final steps towards defeating Voldemort.
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.