You could make an OC who is a dragon rider from a hidden dragon - riding clan. They enter the story during a time of great conflict, and their bond with their dragon is different from what is seen in the show. Their arrival could change the balance of power and the way people view dragons in the world of House of the Dragon.
First, you need to know the lore of House of the Dragon well. Read the books related to it if possible, and watch the show carefully. Then, think about the character you want to create. Decide on their background, like where they come from, their family, and their social status. For example, if your OC is a knight, think about who trained them.
One idea could be creating a male oc who is a skilled healer from a far - off land. He arrives in Westeros during a time of great plague and uses his unique knowledge to try and save lives, which gets him involved in the political intrigues of the court. Another could be a male oc who is a master swordsman, self - exiled from his own house due to a family feud, and he ends up joining the fight for the Iron Throne on the side he believes in. A third idea is a male oc who is a scholar, researching the ancient prophecies of Westeros and trying to influence the events based on what he discovers.
A character like Ser Criston Cole could be a great inspiration. His loyalty, his skills as a knight, and his complex relationship with the Targaryen family can give you ideas for your male oc. Another could be Daemon Targaryen himself. His wild and unpredictable nature, his ambition for the throne, can be elements to incorporate into your oc. Also, characters like Otto Hightower with his political cunning can inspire you to create a male oc who is shrewd in the political games of Westeros.
It's highly unlikely that the characters in 'House of the Dragon' would actually watch fanfiction about themselves. Fanfiction exists in our world, created by fans for fans, and the characters in the show are fictional entities within their own fictional universe. They don't have access to the fan - created stories about them.
Definitely not a true story. House of the Dragon is a work of imagination and creativity. It weaves a complex tale of power, politics, and dragons within a fictional realm.
To create a compelling OC dragon, you need to consider its backstory. Maybe it was exiled from its dragon clan because it didn't conform to their traditions. This backstory can shape its actions and relationships in the Highschool DxD world. Another important aspect is its goals. Does it want to regain its place in the dragon clan? Or is it more interested in making a name for itself in the human world? And don't forget about its relationships with other characters. A rivalry with a devil character or a friendship with an angel can add depth to the OC.