A great plot twist could be that the de - aged Harry discovers that the Triwizard Tournament is being manipulated in a way that no one else realizes. His child - like innocence and fresh perspective allow him to notice small details that others overlook. This could lead to him uncovering a conspiracy within the tournament, and he has to find a way to expose it while still competing.
Maybe the de - aged Harry forms an alliance with a character who in the original story was his rival. Since he's de - aged, he sees things from a different perspective and realizes that they can work together. This could completely change the dynamics of the tournament and how other characters view him.
One interesting plot twist could be that the de - aged Harry has some hidden memories of the future that help him in the tournament in unexpected ways. For example, he might remember a particular spell that an opponent will use and be able to counter it easily.
A plot twist could be that the Triwizard Cup is actually a portal to a different dimension, and Harry and Hermione accidentally get transported there during the final task. They then have to find a way back while dealing with strange creatures and magic in this new dimension.
Maybe in the fanfiction, there's a plot twist where Hermione discovers a hidden rule in the Triwizard Tournament that allows her to form an alliance with all the champions instead of competing against them. This would change the whole dynamic of the tournament and lead to a completely different kind of story.
His relationships can become more innocent. For example, with Hermione, she might be more protective of him as if he were a little brother. Instead of their usual intellectual banter, she could be guiding him more.
One plot twist could be that the Triwizard Tournament itself is a ruse. It was never really about the competition but about luring Harry into a trap. The other champions are unknowingly part of the plan. When Harry discovers this, he has to convince the other champions to join him in fighting against the real enemy behind the tournament.
Perhaps in the fanfiction, Fleur could be in danger during one of the Triwizard Tournament tasks. Harry, being the heroic type, decides to risk everything to save her. This act of heroism not only changes their relationship but also how the other champions and the judges view Harry. It could also lead to some changes in the overall dynamic of the tournament, like new rules being implemented to prevent such dangerous situations in the future.
One possible plot twist could be that Harry is actually in a magically induced coma rather than dead. Maybe a powerful dark spell was cast on him that made everyone believe he was dead, but a hidden ally discovers the truth and tries to revive him. Another twist could be that Harry faked his own death as part of a master plan to expose a great evil within the Triwizard Tournament. He could be secretly working behind the scenes to gather evidence and take down the real villains.
One idea could be a different champion from an unexpected school. For example, a small wizarding school in a far - off land sends a champion. This champion could have unique magic abilities that are not common in Hogwarts, Beauxbatons, or Durmstrang. They might use magic related to nature in a very different way, like communicating with magical plants to solve tournament tasks.
One idea could be a story where a new, unexpected champion enters the Triwizard Tournament. Maybe a student from a different magical school that we haven't heard of before. This new champion could bring unique magic and challenges to the tournament, causing all the other champions to have to adapt their strategies.
One possible scenario in this fanfiction could be that Harry and Fleur form an unexpected alliance during the Triwizard Tournament tasks. They might discover they have complementary skills, like Harry's courage and Fleur's elegance and magic related to water (since she's from Beauxbatons). This alliance could lead to them facing the challenges in a new and interesting way, perhaps with Fleur using her Veela charm in a creative manner to distract the obstacles while Harry uses his Gryffindor bravery to take on the more physical parts of the tasks.
One possible fanfiction could be about Harry and Hermione teaming up secretly during the Triwizard Tournament tasks. They might use their combined knowledge and skills to outwit the other competitors. For example, in the maze task, they could have a special code to communicate and find their way to the Triwizard Cup faster than anyone else.