A possible fanfiction could be that Harry and Fleur accidentally swap magical abilities during a mishap in one of the tournament tasks. This would force them to rely on each other more as they try to figure out how to reverse the situation while still competing. It could be a story full of humor as they struggle with unfamiliar magic, and also of growth as they learn to understand each other's perspectives better.
Yes, there are. Some are well - written in terms of character development. They might show Fleur as more than just a pretty face, and Harry as having a more complex relationship with her than in the original story. For example, a fanfiction could delve into how Harry's experience with Fleur makes him more aware of the wider wizarding world outside of Hogwarts.
One interesting fanfiction could be one where Harry and Ginny secretly team up during the Triwizard Tournament events in the Goblet of Fire. They might use their combined skills and knowledge to solve the various tasks in a different way than in the original story. For example, Ginny could help Harry with the second task by using her knowledge of the Black Lake's secrets that she learned from the Weasley family's stories.
There are fanfictions that might rewrite the whole Harry and Cho dynamic during the Goblet of Fire. For example, instead of the somewhat rocky relationship they had in the original, in the fanfic they could be much closer friends from the start. It could show them training together for the Yule Ball, sharing secrets about their families. Or it could be a fanfic where Cho is actually a key player in helping Harry figure out how his name got into the Goblet of Fire, and their relationship blossoms as they work together to uncover the truth.
One interesting fanfiction could be about the aftermath in the graveyard. Maybe it focuses on how Harry copes with what happened there, like him having nightmares and his friends trying to comfort him. It could also explore the mystery of the dark magic residue left in the graveyard.
There are fanfictions where Fem Harry's character development is more focused on her femininity. In the Goblet of Fire setting, she might deal with the added pressure of looking 'proper' for the Yule Ball. Some fanfictions explore how she uses her intelligence and female charm to get through the tasks in the tournament. For instance, she might use her wits in a different way than the original Harry to outsmart the dragons.
One interesting fanfiction could be about an alternate take on Harry's experience in the Triwizard Tournament. Maybe it focuses on his relationships with the other champions in a way that wasn't fully explored in the original book. For example, a deeper bond between Harry and Cedric.
One interesting plotline could be Hermione and Fleur teaming up to solve a mystery within the Triwizard Tournament. They might use their combined intelligence and skills. For example, Hermione's vast knowledge of magic and Fleur's charm and unique magical abilities could be a great combination to figure out a dark plot against the champions.
In some fanfictions, Harry might know Fleur's insecurities beneath her confident exterior. Maybe he knows that she's under a lot of pressure to represent Beauxbatons well in the Triwizard Tournament. For example, she has to maintain a certain image but might be secretly worried about failing.
One interesting fanfiction could be about a character's rage over being wrongly entered into the Triwizard Tournament. Maybe they feel like they've been set up and their rage fuels their actions throughout the tournament, leading to unexpected twists in the tasks.
One interesting fanfiction could be where Harry's anger at being entered in the Triwizard Tournament against his will leads him to discover a hidden plot much earlier. He might start to suspect that someone within Hogwarts is working against him and begins his own investigation. This could involve him using his skills in a more unorthodox way, like using the Marauder's Map to track the movements of the teachers and other suspicious characters.