It could be a wild dragon from the Forbidden Forest that had some sort of encounter with one of Harry's ancestors. Maybe a female dragon who was drawn to the magic of a powerful wizard in Harry's family tree.
Perhaps it's a dragon that was magically created or transformed by a dark wizard long ago. This dragon then had a relationship with one of Harry's relatives. The dragon might have been a part of some dark experiment that went wrong, but its offspring (Harry) has the potential for great good or great evil depending on how he embraces his heritage.
Well, perhaps Harry could discover he has some dragon - like abilities. Maybe he can breathe a bit of fire when he's extremely angry. It would make him even more of an outcast at first, but then these abilities could help him in battles against Voldemort.
Hermione could help. She's very smart and could research about the dragon's weaknesses.
In this fanfic, perhaps Harry's heritage as the 'Son of the Dragon' is a secret that Voldemort wants to use for his own evil purposes. So, Harry has to not only deal with the regular threats in the wizarding world but also this new danger related to his unique identity. And he might have to seek help from some unexpected allies, like the dragons themselves.
Hermione could be a great help. She's very knowledgeable about magic and could research how to properly care for a newly hatched female dragon.
Obviously, Harry Potter is a main character. Since he is the son of a dragon in this fanfic, his character development would be central. There might also be his friends like Ron and Hermione. They would probably play important roles in helping Harry understand and deal with his new identity. And perhaps there are some dragon characters as well, like his dragon parent or other dragons that he encounters during his adventures.
Obviously, Harry Potter himself. Then there could be the dragons, perhaps an old and wise dragon that acts as Harry's mentor. Hagrid might also play an important role as he has a connection with magical creatures and could help Harry understand his new identity.
There could be many potential authors. It might be an amateur writer who is a huge Harry Potter fan and just wanted to explore this really wild and creative idea. It could be someone within the fanfiction community who is known for their unique and out - of - the - box concepts.
There could be a group of pure - blood wizards who believe that dragons are beneath them and that Harry is tainting the wizarding world by associating with them. They would try to stop Harry from his dragon - related activities, and they might use underhanded tactics like casting spells on him or trying to get him expelled from Hogwarts.
It could be a new student at Hogwarts. A young witch or wizard who has always been fascinated by dragons and finally gets the chance to encounter one and become a rider. This character could bring a fresh perspective to the Hogwarts world.
Maybe a group of dark wizards who are jealous of the power of the dragon knights. They form an alliance to destroy the dragon knights and anyone associated with them, making Harry and his newfound friends their main targets.