Harry Potter himself is often a central character in these fanfictions. Since he was the one who originally faced the dragon task in the Triwizard Tournament, many fanfic authors like to explore different scenarios with him in the same situation.
Hermione Granger also frequently appears. She's known for her intelligence and research skills, so in dragon task fanfictions, she might be the one coming up with new strategies to deal with the dragons or helping others understand the dragons' behaviors better.
Often, original characters are added. For example, a new student who has some special ability related to water or swimming. They might befriend Harry and help him in the second task, either knowingly or unknowingly.
Harry Potter himself is very common. Writers often put him in situations involving dragon spirits to see how he would react and grow. Hermione Granger is also popular as she could use her intelligence to study the dragon spirit, perhaps trying to understand its magic or origin.
Often, Harry Potter himself can be a character in these fanfictions. He might discover his hidden talent for taming dragons. Hermione could also be there, using her vast knowledge to help with the dragon - taming process. Ron could be the one who is initially scared but then warms up to the idea. And of course, Hagrid is likely to be involved as he has a great love for magical creatures, especially dragons.
Ron could also be there. He might be initially scared of the dragon but then grows to like it. His loyalty to Harry would make him support Harry's decisions regarding the dragon, even if they seem risky. For example, when they need to hide the dragon from the Ministry of Magic, Ron would be right there with Harry, coming up with crazy but effective plans.
One possibility could be that Harry, as a Dragon Animagus, uses his new form to his advantage in the First Task. He might be able to outmaneuver the real dragon more easily, flying around it and confusing it. This would give him an edge in retrieving the golden egg.
One interesting plot could be a character having to train a dragon for the task in a completely new way, using magic that was previously undiscovered. This would add an element of mystery and innovation to the story.
If Harry were a Dragon Animagus in the First Task, it would change the whole dynamic. He could use his dragon form to create a diversion. For example, he could make the real dragon chase him away from the egg, and then quickly transform back and snatch the egg. Also, his dragon form might have some special abilities like breathing fire in a controlled way to fend off the real dragon if it attacks.
Hermione Granger is also a popular character. In some fanfictions, she uses her vast knowledge to study dragons in a way that no one has before. She could be researching dragon magic or trying to find a way to communicate with them on a deeper level.
Obviously, Harry Potter is one of the main characters. Since it's a fanfiction about him as a dragon or related to dragons, he would be central. And I think Hagrid would also be an important character as he has a great love for magical creatures, especially dragons. He could be the one to help Harry understand his new relationship with dragons.
Often, the main characters can include the well - known Harry Potter characters like Harry himself. He might get involved with dragons in some way, perhaps during one of his adventures outside of Hogwarts. Another common main character could be a new, original character created specifically for the fanfiction. This character could be a dragon trainer or a researcher of magical creatures, with a special interest in dragons.