There could be new characters introduced as well. Maybe a mysterious wizard from a far - off land who has a significant impact on the story. They could bring new magical knowledge or a different perspective on the wizarding world.
Obviously, Harry Potter would be one of the main characters as the title implies he is born a god. Hermione and Ron are likely to be important characters too, as they are Harry's closest friends in the original series. There could also be new characters introduced, perhaps other powerful wizards or magical creatures who either help or oppose Harry in his new, god - like state.
I'm not sure exactly as I haven't read this specific fanfiction, but likely Harry Potter himself would be a main character since it's about his birth. His parents, James and Lily Potter, are also likely to be important characters in the story.
Hermione and Ron might still be in the story, but their interactions with Harry would be completely changed. Since Harry is a Malfoy, they might initially be enemies or at least very suspicious of him. However, as the story progresses, they could see the good in him that is still there despite his Malfoy background. And Dumbledore would also be an important character, as he might try to guide Harry away from the darker Malfoy influences.
One interesting concept could be new interpretations of the magical world's rules. For example, the way magic is taught or used in ways that differ from the original books. Maybe new spells or magical creatures are introduced.
Draco Malfoy is also a common focus. Fanfiction might show a different side of him, perhaps if he had been born into a more liberal pure - blood family. His complex character and his journey from a bully to someone with more depth in the original series make him an interesting subject for new stories.
In 'Harry Potter Born from Magic' fanfiction, Harry is the central figure, of course. Neville Longbottom might be more prominently featured as well, perhaps having a deeper connection to Harry's magical origin. And then there are the villains. Voldemort or his followers could be important characters as they are always a threat to Harry and the wizarding world.
There could be a wise old wizard who has knowledge about the true nature of the Master of Death and becomes Harry's mentor. Maybe a powerful magical creature that is drawn to Harry's power and offers its assistance.
Hermione is often still a very important character paired with female Harry. Their friendship could be even more complex and deep, as they support each other through the challenges at Hogwarts. Ron is also a common character paired with her. Their relationship might develop in a different way, perhaps with a bit more of a romantic undertone compared to the original. Draco Malfoy is another popular one. There could be a more interesting dynamic between them, with Draco being both attracted and antagonistic towards her at the same time.
The main characters are clearly Dom and Brian. Since it's a fanfiction about them being married, they are at the center of the story. Their personalities, which we know from the original source material, are likely to be key elements in the fanfiction.
Obviously, Harry Potter himself would be the central character as he is the one undergoing the transformation into a born vampire. His friends like Hermione and Ron would also be important characters. They would likely play a role in either helping Harry adjust or being conflicted about his new state.