Obviously, Harry Potter and Severus Snape are the main characters. Harry is the young wizard who is becoming Severus's apprentice.
Sometimes, other Hogwarts professors might make an appearance. For instance, Professor McGonagall could be involved, checking on Harry's progress in both his regular studies and his apprenticeship with Severus. And there could be antagonists as well, like some Slytherin students who might be jealous of Harry getting special attention from Severus, or perhaps some Death Eaters who are still lurking around and pose a threat to Harry and Severus.
There could also be other characters like Hermione and Ron. Hermione might play a role in helping Harry with his studies under Severus, perhaps by researching ancient potions texts. Ron could be there to provide some comical relief or moral support to Harry. And of course, we can't forget Dumbledore, who might be in the background guiding Severus in his task of mentoring Harry, even if it's not always obvious.
Obviously, Harry Potter and Nicholas Flamel would be the main characters. Harry as the apprentice and Flamel as the mentor.
There could be many interesting aspects to such a fanfic. For example, the Squib apprentice might struggle with feeling out of place in a world full of magic, yet be drawn to Severus's knowledge. Maybe they learn non - magical ways to assist in potion - making or herbology tasks. They could also face discrimination from other wizards due to being a Squib, but find acceptance and purpose under Severus's tutelage.
Another plot could involve Severus training Harry to be a better Occlumens. As Harry delves deeper into this art, he uncovers some of his own hidden memories and emotions. This could lead to a better understanding between Harry and Severus as they share their experiences with mind - protecting magic. It also might put Harry in a position where he can better defend himself against Voldemort's attempts to invade his mind.
The apprentice is obviously one of the main characters. They are likely to be a young wizard or witch with great potential. Then there might be characters representing the different houses of Hogwarts, like a descendant of Gryffindor who is a mentor to the apprentice. There could also be a rival apprentice who has different ideas about the founders' magic.
One possible plot could be that the Squib apprentice, despite not having magic, has a deep understanding of the magical world's history and lore. Severus discovers this and takes the Squib under his wing. Together, they might uncover some long - forgotten secrets about Hogwarts or certain potions. As they dig deeper, they face opposition from some traditional wizards who don't believe a Squib should be involved in such important matters.
Obviously, Harry Potter would be one of the main characters. And Naga Sadow, as the one Harry is apprenticed to. There might also be some of Harry's friends from Hogwarts like Hermione and Ron, who could be trying to bring him back from the dark path he's on.
Another possible main character could be a new villain. Since Harry is in a new role as an apprentice, there could be someone who wants to steal the secrets of Ollivander's wand - making. This villain could be a dark wizard or a rogue wizard who has his own motives for wanting to control the wand - making process. Harry would then have to protect Ollivander and the shop from this threat.
It could be an original character created just for the fanfic. Maybe a young wizard or witch who has a special talent for alchemy and catches Flamel's eye.
The two main characters are obviously Severus Snape and Harry Potter. Severus is the one who adopts Harry, changing from his usually cold and aloof self to a more caring and protective figure. Harry is the abused child who gets a new chance at a better life under Severus's care.
It's Harry and Severus. Harry, who has been through so much in the fight against Voldemort, and Severus, whose loyalty was always in question but ultimately was on the side of good. In this fanfic, they are the central figures as they embark on this new adventure in Forks. They will probably have to rely on each other more than they ever have before, given that they are in a completely new and unfamiliar place.