One interesting plotline could be Harry fully exploring and mastering the powers that come with being the Master of Death. He might use these newfound abilities to reshape the wizarding world, like eliminating dark magic at its roots.
Perhaps in some fanfictions, Harry, as the Immortal Master of Death, travels through different time periods in the wizarding world. He could meet ancient wizards and witches, and learn forgotten magic that he then brings back to his own time to defeat new threats.
One interesting plotline could be Harry's journey to fully understand and master the power of being the Master of Death. He might face challenges from dark wizards who are envious of his newfound status.
One interesting plotline could be Harry fully exploring and mastering the powers that come with being the Master of Death. He might use these powers to reshape the wizarding world in ways that were not possible before, like eradicating dark magic at its source.
One possible plotline could be Harry exploring the full extent of his newfound power as the Master of Death. He might use it to bring back loved ones in a way that doesn't disrupt the balance of the wizarding world. Another could be that he faces new and more powerful enemies who are threatened by his status.
Another plotline might involve Harry's journey as the Master of Death leading him to discover new magical realms. He might travel to places that are beyond the veil in a more permanent and controlled way, and bring back knowledge or magic that could revolutionize the way wizards and witches in the known world practice magic.
One interesting plotline could be a deeper exploration of the Hallows' true powers. Maybe the characters discover new ways to use the Elder Wand, Resurrection Stone, and Invisibility Cloak that J.K. Rowling didn't fully explore in the original series. Another could be a different take on the final battle against Voldemort, with the Hallows playing a more complex role.
One possible plotline could be that Harry discovers a way to communicate with Death as an entity. Maybe he stumbles upon an ancient magic that allows him to have conversations with Death. Through these interactions, he gains a deeper understanding of life and death, and this new knowledge helps him in his battles against Voldemort. For example, Death could give him insights into the Horcruxes and how to destroy them more effectively.
In the fanfiction, it could be that Harry's friendship with Death is a secret known only to a few. He has to hide it from most of the wizarding world because they would not understand. This secrecy could add a lot of tension to the story. For instance, when strange things start to happen around Harry, like people seeing shadowy figures or experiencing unexplained chills, some might suspect dark magic. But in reality, it's just a side - effect of his connection with Death. Harry would have to struggle to keep his friendship a secret while also using the knowledge he gains from Death to protect his friends and the wizarding world.
A possible plotline could be the apprentice's journey to understand the true nature of death. In the fanfiction, they could be on a quest to find out the secrets behind the veil in the Department of Mysteries. Along the way, they encounter various challenges and make new allies, all while trying to master their role as the apprentice of death.
A great plotline in such fanfiction could be a Potion Master being framed for creating a harmful potion. The real culprit might be someone trying to discredit the Potion Master for personal gain, like a rival for a teaching position at Hogwarts. The Potion Master then has to prove their innocence while also dealing with the chaos that the false accusation has caused in the wizarding community. They might have to enlist the help of their students or former colleagues to clear their name.
In some fanfictions, Harry's time - mastery allows him to interact with past versions of himself. This can create really complex and mind - bending scenarios. He could use these interactions to gain wisdom from his past experiences more directly, or to give his past self crucial information that would help him in his battles against Voldemort. For instance, he might tell his younger self about a hidden weakness of a particular Death Eater that he discovers in the future.