In some fourth - year Harry Potter AU fanfictions, a possible plot twist is that Harry has a long - lost twin. During the fourth year, this twin shows up at Hogwarts. This twin could be under the influence of a dark wizard and tries to undermine Harry's standing at Hogwarts. Or perhaps the Goblet of Fire chooses both Harry and his twin to compete in the Triwizard Tournament, which creates a whole new set of rules and challenges as they have to work together in some tasks and compete against each other in others.
Well, a cool plot twist might be that in this 4th - year AU fanfic, the Triwizard Tournament tasks are all designed by a rogue Death Eater who has infiltrated Hogwarts' staff. So the tasks are not just tests of courage and skill but also traps to try and harm the students. Also, Harry might discover that his parents were actually part of a secret society within the wizarding world that was fighting against a different dark force, not just Voldemort, which changes his whole perspective on his family and his role in the wizarding world.
One interesting plot twist could be that in the AU, Neville Longbottom is the one secretly chosen for the Triwizard Tournament instead of Harry. It would completely change the dynamic as Neville has his own insecurities and strengths that would play out differently in the challenges.
A great plot twist could be that the Dementors are being controlled by someone other than the Ministry. They start attacking students more frequently and specifically target Harry because they are being used to find something that Harry unknowingly has. This would make the already dangerous situation in the third year even more intense.
Maybe in this fanfiction AU, the relationship between Harry and Hermione develops romantically during the fourth year. This would change the dynamics of their friendship and how they interact with Ron. They could face challenges together in the tournament, relying on their newfound feelings to get through difficult situations.
One idea could be that Harry discovers a new, hidden magical ability within himself that helps him in the final battle against Voldemort. For example, the ability to communicate with the spirits of Hogwarts founders for guidance. Another could be that the relationships between the characters take a different turn. Maybe Hermione and Ron have a huge fight early on and Hermione teams up with Draco for a while out of necessity, which changes the dynamics of the whole group. Also, Neville could have an even more prominent role, leading a secret group of students who are training in a new form of magic that they hope will give them an edge in the fight.
A really cool plot twist might be that Hermione finds a way to travel back in time to change certain events that led to Voldemort's rise. She has to be extremely careful not to disrupt the whole timeline while trying to save the wizarding world. It's a complex and exciting idea that can lead to a lot of interesting scenarios in the 7th year of the story.
In AU 4th - year fanfictions, relationships can change a great deal. For example, if Harry was raised by Sirius instead of the Dursleys. His confidence might be higher, and his relationship with Draco could be less antagonistic from the start. Maybe they could even become reluctant allies in the face of a new threat at Hogwarts. Also, Hermione might form a closer bond with Neville as they study together more often in this AU, and Ron could become a bit jealous of their newfound friendship.
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.
One interesting plot twist could be that a minor character from the previous years turns out to be a key figure in the fight against Voldemort. For example, a Hufflepuff student who was always in the background might have some secret knowledge or power that helps Harry in his final battle.
One idea could be exploring a different version of the Triwizard Tournament. For example, what if there were more magical creatures involved in the tasks? Another could be focusing on Harry's relationship with Sirius during that year in a more in - depth way, like Sirius secretly guiding Harry through some of the tournament challenges. Maybe also a plot where a new student arrives who has a connection to Voldemort's past that no one is aware of and they try to disrupt the tournament.
A fanfiction could also be about Harry's relationship with his parents during his fourth year. Through some magical event, he gets to communicate with their spirits or memories more vividly. This could help him understand his parents better and also give him strength and guidance for the challenges he faces in that year.