In some cases, there might be new original characters created specifically for the fanfiction. These could be characters who have a connection to the ancient magic of Merlin and Morgana. For example, a mysterious wizard who has been guarding an artifact related to their power. They could initially be an enigma to Harry and his friends, but as the story progresses, they become an important part of the plot, either as an ally or an adversary.
Then there are the other members of the Black family, either alive or in portraits. They could be sources of information, guidance, or obstacles for the heir. For example, Walburga Black's portrait might be constantly berating the heir or trying to steer them in a more traditional, dark - leaning direction of the family's history.
The heir of the Black family is the key character, of course. But other characters like Hermione Granger could also be involved. She could help the heir with her vast knowledge of magic. And Dumbledore might also show up, as he has a deep understanding of the wizarding world and could offer advice or warnings to the heir.
Well, of course, the heir of Morgana is likely to be a main character. They would be the focus as they navigate their new identity and the powers that come with it.
Obviously, Harry Potter is a main character as the heir of Merlin. Hermione Granger is often included as she helps Harry figure out the implications of his new status and the mysteries that come with it. Ron Weasley might also be there, providing his usual loyalty and friendship.
Harry Potter himself is often a main character. Since it's a fanfiction related to his world, he might be the one to inherit something from Merlin. For example, he could inherit Merlin's wand or a special magical ability that Merlin had.
Hermione could be a main character. She might help Harry understand the implications of being heir to multiple houses. Ron could also be important as he stands by Harry through all the new revelations. There could also be characters like Draco Malfoy. If Harry is heir to Slytherin, Draco's attitude towards Harry might change significantly, adding an interesting dynamic to their relationship.
Dumbledore is often a main character in Harry Potter 1945 fanfiction. Since he was around during that time, many stories explore his youth, his friendships, and his early battles against the dark forces.
Hermione and Ron are likely to be main characters too. They are Harry's closest friends in the original series, and in this fanfiction, they would probably play important roles in helping Harry understand and deal with his new identity as Merlin's heir. They might assist him in researching about Merlin, or they could be by his side when he faces new challenges because of this heritage.
Often, Harry Potter himself might be a main character in such fanfiction. The idea of him having some daywalker - like abilities could be explored, perhaps as a result of a strange encounter or a new form of magic. Hermione Granger could also be a key character, using her intelligence to help Harry understand and control his new powers if he were to become a daywalker.
Some fanfictions might also focus on lesser - known characters from the Sacred 28 families. Maybe a minor Prewett or a Weasley relative that we don't know much about in the original books. They could be given a more prominent role, perhaps as a hero or a villain within the Sacred 28 - related storylines.