One common theme is the power of the Philosopher's Stone. Since Flamel is associated with it, many fanfictions explore how the Stone's power can be used or misused. For example, some stories might have villains trying to steal it again for their own dark purposes.
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.
One possible plot could be that Harry grows up learning ancient alchemy from Flamel. He might be trained in the secrets of the Philosopher's Stone from a very young age, giving him a different perspective on magic compared to his canon self. Maybe he'd have a deeper understanding of life - extension magic and use it to help others in the wizarding world.
Many fanfics focus on Flamel's role in the wizarding world's history. They might show how his actions in the past have shaped the present situation in the wizarding world that Harry finds himself in. Some fanfics also have a plot point where Flamel's power is slowly fading, and Harry has to find a way to either restore it or use the remaining power to defeat Voldemort. There could also be a plot where Flamel has a prophetic vision about Harry and his destiny, and the story then revolves around how Harry tries to fulfill that destiny with Flamel's guidance.
There is a fanfic called 'Nicholas Flamel: The Untold Story in Harry Potter's World'. In this fanfic, the author tries to fill in the gaps about Flamel that were not fully explored in the original books. It gives a more in - depth look at his life, his magic, and his connection to the Philosopher's Stone. And also, 'Harry Potter and Flamel's Guidance' is quite interesting, where Flamel plays a more direct role in guiding Harry through some difficult situations.
Perhaps Nicholas Flamel, being extremely old and wise, trains Harry in a very different way than Dumbledore or the Hogwarts professors. He might focus on teaching Harry about the balance of magic and nature through alchemy, which gives Harry a new perspective on magic and how to use it against the Dark Arts.
In such a fanfiction, perhaps Harry would learn ancient and powerful magic from Nicholas Flamel. Flamel, being the creator of the Philosopher's Stone, could teach Harry secrets about alchemy and immortality. Harry might gain new powers and a deeper understanding of magic that could change the course of his battles against Voldemort.
One great 'Harry Potter Nicholas Flamel' fanfiction is 'The Alchemist's Legacy'. It delves into Flamel's past and his connection to the wizarding world in a really interesting way. The story has a great plot that keeps you hooked from the start.
His character would likely become more mature. Learning from Flamel, an ancient and wise wizard, would expose Harry to different values and ways of thinking. He might become more patient and less impulsive in his actions.