One plot idea could be that during the Triwizard Tournament, Harry and Mirajane are paired for one of the tasks. They have to work together to overcome some magical creatures. Harry's quick thinking and Mirajane's unique magic skills combine to make them a formidable team.
Well, it could start with simple curiosity. Harry might be intrigued by Mirajane's different magical abilities compared to what he's used to at Hogwarts. And Mirajane could be interested in Harry because of his fame. As they interact more during the Triwizard events, they start to respect each other's skills and personalities.
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.
It could be Dumbledore in a lot of fanfictions. Dumbledore often plays a key role in these stories and his reasons for summoning Harry could vary. Maybe he wants Harry to prove himself in a different way, or he has some premonition about the tournament that only Harry can help with.
In a fanfic like this, there could be a lot of drama. For example, Pansy might be conflicted because of her Slytherin loyalty and her growing feelings for Harry. Harry, on the other hand, could be dealing with his own feelings while also trying to survive the dangerous tasks of the Triwizard Tournament. Their relationship could start with a lot of bickering and then slowly turn into something more romantic as they face the challenges together.
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.
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.
A big theme is the idea of loyalty. In these fanfics, Harry and Daphne show loyalty to each other, especially when dealing with the dangerous situations in the Triwizard Tournament. Also, the theme of mystery is prevalent. Daphne might have some secrets that are gradually uncovered as the story unfolds within the context of the Triwizard Tournament.