Albus Dumbledore himself can be central to many conspiracy fanfictions. There could be theories that he was aware of a powerful dark magic influence in the Ministry of Magic all along and was using Harry as a pawn in a bigger game to expose and defeat it. He might have had ulterior motives for his actions throughout the series that go beyond what was initially presented.
Hermione Granger is often involved. In some fanfictions, she discovers hidden conspiracies within the Hogwarts library. For example, she might find a book that reveals a plot by some of the older pure - blood families to keep certain magical knowledge from half - bloods and Muggle - borns.
Severus Snape is also a common character. Fanfic writers might create a conspiracy where Snape's loyalty to Dumbledore was part of a much larger scheme. Maybe he was working for an underground group that wanted to reform the wizarding world from within, and his actions as a double - agent were part of a long - term strategy.
Mrs. Weasley is a very likely character. She's an expert at cooking and baking in the normal wizarding world, so in fanfiction about magical bakes, she could be teaching the younger characters how to make special bakes. Hagrid might also be involved. He could bring in some really strange ingredients from the Forbidden Forest, like giant acorns, to be used in the bakes.
Some fanfictions may also introduce original characters who are related to known wizarding families. For example, a long - lost relative of the Black family. These characters can bring new perspectives on inheritance. There could also be characters from other magical cultures or regions who have their own unique inheritance systems that interact with the more familiar Harry Potter world inheritance ideas.
Harry Potter himself is often involved. His inheritance from his parents, like the Invisibility Cloak and his family's magical abilities, can be a central part of the story. There could be situations where others suspect he might use his inheritances in a way that betrays the wizarding world, like if he was somehow influenced by the dark side of his family's magic.
Obviously, Harry Potter himself is the central character in this type of fanfiction. Then there are often characters like Voldemort or his Death Eaters, as they are the ones Harry would be changing sides to. Bellatrix Lestrange could be a key figure in trying to persuade Harry or manipulate him into joining their side.
Besides the main trio, Professor Dumbledore can be a significant character in such fanfictions. His wisdom would be invaluable in guiding the use of advanced technologies. Severus Snape might also be involved, perhaps using his potion - making expertise to develop new potions - related technologies. And then there are the Weasley twins. They are always up for some new and exciting inventions, so they would fit right into the concept of advanced technologies in the Harry Potter universe.
Harry Potter himself is often involved. Writers might explore how he could use the magic eye in different ways to solve mysteries or fight against the dark forces. Hermione would also be a common character. She could study the magic eye and try to understand its mechanics and magic better.
Obviously, Harry Potter himself is the central character as the title implies. Voldemort is also often involved as the main figure on the 'dark side' that Harry might switch to or interact with differently. Then there's Snape. His complex relationship with Harry could be a key factor in the story. In some fanfictions, he might be the one who either tempts Harry to switch sides or tries to prevent it depending on his own motives.
Oliver Wood is another character that might be in such fanfiction. He's extremely passionate about Quidditch. In a harem - related Quidditch fanfiction, he could be the object of affection for some students who are attracted to his dedication and skill on the pitch. Also, the Weasley twins, Fred and George, could be involved. Their mischievous nature combined with their Quidditch skills might draw a group of followers or love interests.
Harry Potter himself is often a central character. The truth serum might be used on him, or he could be the one trying to find out the truth from others. Hermione Granger is also common, as her intelligence might be used to either create or counteract the effects of the truth serum.
Luna Lovegood could be involved too. She has a unique perspective on magic and the wizarding world. Her presence in the fanfiction could add an interesting and quirky element, especially if she helps Harry in his new situation, perhaps with her knowledge of strange magical creatures or her intuitive understanding of magic.