As the plot progresses, Harry might start to realize the true extent of what he's gotten himself into. He could face internal struggles, doubting his decision. Maybe he'll discover some secrets about the Goblet or the tournament that he wasn't supposed to know. This could lead to a whole new set of challenges and adventures, like having to deal with dark magic associated with the tournament that was hidden from the public.
Another consequence could be that he has to face opponents in the tournament that are far more experienced or dangerous than he expected. In fanfic, the author might make these opponents even more formidable to test Harry in ways that the original tournament didn't. Also, his relationship with Cedric could be severely strained as they are now direct competitors, which could lead to some intense rivalries and emotional drama.
In the fanfic, Harry might use his quick thinking and knowledge of magic. He could trick the Goblet by using spells to misdirect its selection process. For example, he might create an illusion of another person's identity so the Goblet chooses based on false information.
One consequence could be that he gets into trouble with the school authorities. They might suspect foul play and start an investigation into how he managed to fool the Goblet.
Well, I really like the fanfic 'Feminine Fire'. In this story, the female Harry has a unique charm. She approaches the challenges of the Goblet of Fire in a very different way compared to the original male Harry. For example, her interactions with Cedric are more nuanced and there are some really interesting plot twists. Another good one is 'Goblet of Fire: Female Edition' which not only changes Harry to a female but also tweaks the overall magical world a bit to fit the new narrative.
One great fanfic could be about Harry and Hermione getting unexpected advice from McGonagall regarding the Goblet of Fire. Maybe McGonagall suspects some foul play early on and warns them to stay away from it, but their curiosity gets the better of them.
It could be Sirius Black. He has a lot of experience in the wizarding world and, despite being on the run, he could find a way to communicate with Harry secretly. He could teach Harry about dark magic defense, which would be very useful in the tournament.
Well, perhaps in this fanfic, the Goblet of Fire might summon Harry in a different way than in the original story. Maybe it has a mind of its own and specifically targets Harry for a more dangerous and secretive task that the original Triwizard Tournament didn't include.
The fanfic might revolve around Harry's interaction with the Goblet of Fire due to a misunderstanding. He could think that the goblet is being influenced by dark magic and decides to investigate. As he messes with it, he discovers some hidden secrets about the Triwizard Tournament and its origins. This could lead to him having to make difficult choices to protect the integrity of the tournament and Hogwarts, all while dealing with the consequences of his meddling with such a powerful magical object.
One interesting fanfic could be where Harry and Hermione team up to solve the mysteries behind the Goblet of Fire in a more in - depth way than in the original book. Maybe they discover a hidden plot early on and work together to expose it.