How about Sirius Black? He has a different view of magic compared to the traditional Hogwarts professors. He could teach his apprentice how to think outside the box and use magic in more unorthodox ways. Also, he could pass on his knowledge of the wizarding world's secrets and hidden places.
Dumbledore would be an excellent choice. He is extremely powerful and wise. His apprentice would learn not only about powerful spells but also about the greater good and moral responsibilities that come with magic.
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.
One possible fanfic could be about Harry Potter starting his apprenticeship at Gringotts and uncovering secrets about the bank's vaults. He might learn about the magical security systems and the history of some of the most powerful magical artifacts stored there.
Another option could be Luna Lovegood. She has a very unique perspective on magic already. If she were Merlin's apprentice, she could bring her eccentric ideas and combine them with Merlin's ancient magic. Her friendship with Harry Potter and the others could also play a big role in how she uses her newfound status as Merlin's apprentice to help the wizarding world.
It could also be a character from outside of Hogwarts. Maybe a young wizard who has been self - taught in some dark magic and Dumbledore takes them as an apprentice to guide them towards the light side of magic. Dumbledore would see the potential for good in this character and want to reform them.
Obviously, Harry Potter and Severus Snape are the main characters. Harry is the young wizard who is becoming Severus's apprentice.
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.
The plot could revolve around Harry's apprenticeship under Nicholas Flamel. Harry might be chosen because of his unique connection to Voldemort. Flamel could see that Harry has a special destiny and decides to train him in the ways of alchemy. This could include learning how to transmute substances, understand the properties of magical elements, and use alchemy for defense and offense. Harry could also learn about the history of magic through Flamel's eyes, which is much longer and deeper than what he has learned at Hogwarts. There could be a lot of adventures where Harry uses his newfound alchemical knowledge to fight against the forces of evil.
Perhaps Harry discovers a long - lost magical item in one of the vaults during his apprenticeship. This item could be of great importance to the wizarding world, and he has to decide whether to keep it a secret or reveal it to the authorities. Along the way, he has to deal with the greed and envy of some of the other employees at Gringotts.
Yes, often there are unique plots. For example, the apprentice might get involved in secret alchemy experiments Flamel was famous for. They could discover new magical potions or spells, and have adventures in the wizarding world that are different from Harry's main story in the original books.
The apprentice's character development can be shown through their changing views on magic. At first, they might be in awe of Grindelwald's powerful and often dark magic. But as they learn more, they start to see the harm it can cause. For example, if they witness Grindelwald using a spell to harm innocent people, it could make them question their loyalty.