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.
Hermione could still be a common character. Even in fanfiction where Harry is alone, Hermione might be mentioned in his thoughts or in flashbacks as someone who has influenced him. For example, he might recall her advice on how to study magic when he is facing a difficult spell alone.
In some fanfictions, there could be a magical creature that has somehow found its way into the orphanage. For example, a house - elf might be there, either sent by someone to protect Harry or just lost. This house - elf could be a key character in the story, helping Harry with small tasks and providing some comic relief. There may also be a character from the Ministry of Magic who is sent to check on Harry's well - being in the orphanage, and this person could have their own motives and secrets.
Hermione would probably be there. She's Harry's best friend and always helps him in his adventures, so in a fanfiction about Harry discovering his heritage, she would be by his side, using her vast knowledge to help him figure things out.
Ron could also be there. He might be a bit jealous at first if Harry's adopted family is wealthier or has more influence in the wizarding world. But later, he would support Harry as always.
His friends from the original story could also be main characters. For example, Hermione might be there, constantly worried about Harry's dangerous dragon - riding adventures but also helping him with research about dragons and their habitats.
Maybe Neville could be involved too. He has shown great courage in the original series. In this fanfic, he could be the one who has some prior knowledge about the dragon due to his family's history in the wizarding world. His knowledge could be crucial in helping Harry enter the dragon's territory and deal with whatever lies within.
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.
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.
Besides Harry, Hermione is a key character. She can research and find loopholes in the Ministry's laws and regulations. Ron is there too, providing muscle and emotional support. Neville Longbottom could also be involved. He has grown into a strong and brave wizard, and he might join Harry's cause. Additionally, Luna Lovegood with her unique perspective on magic could offer different ways of approaching the conflict with the Ministry. Some fanfictions might also include Sirius Black, if set in a timeline where he didn't die, as he has a history of opposing the Ministry's unjust actions.