Harry Potter is the central figure for sure. Since it's about him finding the Helm of Fate. Ron and Hermione are bound to be involved as they are Harry's closest friends. There could be a villain or antagonist as well, someone who doesn't want Harry to find the Helm. It could be a dark wizard or a power - hungry character. And there might be some side characters from the wizarding world, like teachers from Hogwarts or members of the Order of the Phoenix, who might play a part in Harry's journey.
The main character is Harry Potter. He is the one on the mission to find the Helm of Fate. Ron and Hermione will be there to support him. There could be a mysterious figure who has been waiting for someone to find the Helm for ages. This figure could be either good or bad. There may also be some magical creatures that Harry has to interact with during his search, like a centaur or a phoenix. These could be considered important characters in the fanfiction as they help or hinder Harry's progress in different ways.
Well, this fanfiction could start with Harry having a strange vision or finding an old prophecy about the Helm of Fate. He then sets out to find it. Along the way, he could encounter different wizarding cultures and magics that he didn't know before. The Helm of Fate could be protected by powerful spells or guardians. Harry might have to learn new spells or skills in order to overcome these obstacles. Once he finds the Helm, he may discover that it has a connection to his own fate or the fate of the wizarding world as a whole, and he has to make a difficult decision on how to use it.
Obviously, Harry Potter himself would be a main character. He could bring his skills and courage from the wizarding world to the Battle of Helm's Deep. Hermione Granger would also be there. Her vast knowledge of magic could be crucial in finding solutions during the battle. Ron Weasley too, with his loyalty and his own brand of wizarding skills. Maybe Hagrid could also be involved, his huge size and strength being an asset in the physical combat at Helm's Deep.
Obviously, Harry Potter is one of the main characters. His character would be explored in a new light as the 'Son of Fate'.
Often, Harry Potter himself remains one of the main characters. Since the fanfiction is about manipulating fate, it usually revolves around his fate being changed or him being the one to change others' fates.
It's likely that Harry Potter himself would still be one of the main characters. Hermione and Ron would probably also play important roles. However, there could be new characters introduced as well that are central to the new order concept.
Well, in this fanfiction, Harry is surely the central figure. But there could be some side characters that gain more prominence due to the fate's debt. Maybe a long - lost relative of Harry's shows up because of the debt's implications. Or an old wizard who has been waiting for the right moment, which is brought about by the fate's debt, to come forward and help Harry. So, while the core characters from the original series are important, new elements can be added through this concept of fate's debt.
In this fanfiction, Harry Potter is the obvious main character as the story seems to revolve around him getting a second chance. Besides him, characters like Ginny Weasley could be important. If the story is about changing relationships, Ginny's relationship with Harry could be explored in a new light. Also, characters from the Ministry of Magic might be involved if Harry's second chance has political implications in the wizarding world.
Well, Harry Potter himself is likely still a main character. He's at the center of so much in the original series, so he'd probably be central here too.
It could be a dark wizard who wants to get his hands on the lightsaber for its power. He might see it as a new tool to use in his evil plans, like using it to break into Gringotts or to fight off any who oppose him.
It could be a dark wizard who also has an interest in the snake. Maybe he wants to use the snake's powers for evil purposes, like opening a portal to a dark dimension or controlling other magical creatures. So he becomes the main obstacle for Harry as he tries to protect the snake.