In some fanfictions, the Triwizard Tournament tasks are altered in a way that forces Harry and Hermione to rely more on each other. Maybe there are tasks that specifically require their combined knowledge of magic. This creates a situation where they grow closer and their relationship evolves. There are also stories where Voldemort has a different plan related to the Tournament that involves using Harry and Hermione's relationship to his advantage, which leads to a lot of tense and exciting moments.
One common plotline is that Hermione participates in the Triwizard Tournament instead of Cedric. This gives her and Harry a whole new dynamic as they face the challenges together. Another plotline could be that there's some sort of magical interference during the Tournament that makes Harry and Hermione realize their deeper feelings for each other. For example, a spell gone wrong that makes them share their innermost thoughts.
A really cool plotline could be that the Triwizard Tournament tasks are all connected to an ancient prophecy that only Harry and Susan can figure out. They start to notice strange symbols during the tasks that lead them on a hunt through Hogwarts' secret passages to uncover the truth behind the prophecy.
A common plotline is that of Hermione and Fleur teaming up against the other competitors. This is interesting as it subverts the expected rivalry. They can use their combined strengths to overcome challenges that neither could face alone. For example, Hermione's strategic thinking paired with Fleur's beauty - based magic can be a formidable combination in tasks like the maze.
A possible plotline is that Luna enters the Triwizard Tournament as an unexpected champion. Harry, already in the tournament, teams up with her to face the challenges. They use their combined skills, Harry's Gryffindor courage and Luna's Ravenclaw wisdom, to overcome 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.
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.
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.
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.
A plot could be that the Triwizard Tournament tasks are magically altered to target Harry specifically, and Hermione has to use her skills to figure out who is behind it. Maybe a new dark magic is involved that she has to research. She then has to train Harry in new ways to face the challenges. For example, teaching him some ancient spells that are not commonly known.
There could be a plot point where Fleur's Veela heritage causes problems during the tournament. For example, it might attract unwanted attention from some of the creatures in the tasks, like the dragons in the first task. Harry has to use his quick thinking to protect Fleur and keep her focused on the task at hand. This could lead to some comical as well as intense situations as they try to deal with the chaos caused by her Veela charm.
Well, perhaps in the fanfic, Harry and Hermione find out that the dragons are actually magical guardians protecting a powerful ancient artifact within the tournament arena. They then have to decide whether to compete against the dragons as the rules state or try to work with them to uncover the mystery of the artifact. And also, the dragon that Harry is supposed to face in the tournament could have a special connection to his past that Hermione helps him uncover.