It's possible that the main characters in 'a better fate fanfiction' are a combination of beloved characters from the original and some original characters created by the fanfiction author. These new characters could be there to introduce new conflicts or to be the catalysts for the existing characters to strive towards a better fate.
It's hard to say without actually reading the fanfiction. It could be the underdog character who is seeking a new start in life. Maybe it's a young adventurer who has been down on their luck and this chance to change fate is what sets them on a new path.
Obviously, Naruto would be one of the main characters. Since it's about him being favored by fate. But there could also be other characters like Sasuke, who might be involved in Naruto's fated journey, either as a friend, rival or an important part of the overall plot.
In this fanfiction, the main characters are probably Bella, Edward, and Jacob. Since it's a Twilight - based story, these are the central figures in the original series. Bella is the human who gets involved with the vampire Edward and the werewolf Jacob. Their complex relationships would surely be a part of this fanfiction. However, there could also be other secondary characters from the Twilight universe that play important roles depending on how the story of fate unfolds for them.
Obviously, Merlin is one of the main characters. He is a powerful wizard with a great destiny.
Obviously, Medea and Sakura are the main characters. Medea is a well - known figure in the Fate series, with her powerful magic. Sakura, too, has her own story and character traits, and in this fanfiction, their relationship as an adoptive mother - daughter or mentor - mentee is the central focus.
Obviously, Harry Potter is one of the main characters. His character would be explored in a new light as the 'Son of Fate'.
Obviously Naruto is one of the main characters. But there could also be his friends like Sasuke and Sakura. They might play important roles in Naruto's journey to becoming the master of his fate, either as supporters or as characters who present challenges for him to overcome.
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.
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.