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.
Voldemort would be a common character too. Since he is Harry's main antagonist, in stories where Harry is alone, the threat of Voldemort would be ever - present. Harry might be alone in his attempts to find a way to finally defeat Voldemort, whether it's by seeking out new magical powers or trying to outwit him in a one - on - one encounter.
Dumbledore is also likely to be in these fanfictions. He is such an important figure in the Harry Potter universe that his presence, even in the form of memories or through his lingering influence on Hogwarts, would be felt. Harry might think about Dumbledore's words of wisdom as he struggles alone in different situations.
Hermione could still play a major role. She might be the first person to reach out to Harry when he finally enters the wizarding world. Since Harry grew up alone, he would be very different, and Hermione's inquisitive and helpful nature would be drawn to him. She could help him catch up on all the things he missed out on growing up alone.
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.
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.
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.
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.
Hermione Granger often appears. Since she is Harry's best friend in the original series, she can play an important role in helping Harry understand the new alternate universe. Ron Weasley is also common. His loyalty and humor can add interesting elements to the story. Dumbledore might also show up. His wisdom can be crucial in guiding Harry in the strange new world.
Harry Potter is often a common character. His relationship with Snape was complex in the original series, and in fanfiction where Snape is a father, it can add another layer of complexity. Harry might be involved in some way, either as an ally or an antagonist to Snape's new - found family situation.
Draco Malfoy is a very common character. Since they are in the same house in this fanfiction concept, their interactions would be different from the original story. There would likely be more opportunities for them to either become friends or rivals in a new way.
There could be some original characters created by the fanfiction authors. These could be Harry's new classmates or friends at Durmstrang. They might have their own unique magical skills and personalities, and through their interactions with Harry, they can help develop the story further. For example, a new friend could introduce Harry to a secret part of the Durmstrang grounds or a special magical technique that's unique to the school.
Often, there are advisers or mentors. These are characters who have a lot of knowledge about the monarchy and its workings. They might be old nobles or wise scholars who help Harry understand the ropes of being the heir. There could also be antagonists like power - hungry nobles who see Harry as a threat to their own ambitions and try to get rid of him.