One possibility could be that Harry discovers some dark magic or a hidden conspiracy within the Triwizard Tournament that forces him to take extreme measures and destroy it. Maybe he finds out that the tournament is being used as a cover for an evil plot against Hogwarts or the wizarding world in general.
It could be one of the headmasters or organizers of the Triwizard Tournament who has a hidden agenda. They might be using the tournament for their own gain, perhaps to gain power or wealth, and Harry's actions to destroy it are thwarting their plans.
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 great fanfiction could be where Harry and Luna team up in a unique way during the Triwizard Tournament tasks. Maybe Luna uses her off - beat magical knowledge to help Harry solve the puzzles in the maze. For example, she might recognize some magical creatures that Harry is unfamiliar with and guide him through.
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.
In some fanfictions, the author might explore the idea that the person who dragged Harry into the Triwizard Tournament has a personal vendetta against him. Maybe it's a relative of a Death Eater who wants to see Harry fail publicly or even die during the tournament. Harry then has to not only survive the tasks but also figure out who is behind this plot against him.
Maybe in fanfiction, Harry hates the Triwizard Tournament because it brings too much danger and unwanted attention. He has to face powerful opponents and deal with complex rules that he may not be fully prepared for.
One possible fanfiction could be about Harry getting amnesia during the Triwizard Tournament and Luna being the one to help him remember. Maybe she uses her unique perspective and knowledge of magical creatures and odd things to jog his memory. For example, she might take him to see the Thestrals, which are associated with death and memory in the wizarding world.
The fanfiction could take an interesting turn if the dark elf part of Harry was somehow tied to the origin of the Triwizard Tournament. Perhaps there was an ancient dark elf magic involved in the creation of the tournament, and Harry, being part dark elf, has a special connection to it. He could then uncover secrets about the tournament that no one else knew, which could give him an edge in the tasks.
There might be a fanfic where during the Triwizard Tournament, Harry gets cursed and Hermione has to find a way to break the curse. She races against time, using every spell and potion she knows. Meanwhile, she also has to deal with the tournament tasks on Harry's behalf. In the end, through her determination and love for Harry, she manages to break the curse and they both complete the tournament in an unexpected way.