Perhaps Harry, as the Young Master of Death, has to deal with the jealousy and fear of other wizards. Some might try to steal his power or use it for their own evil purposes. He could form an alliance with some unexpected characters, like the ghosts in Hogwarts, who help him understand and control his powers better.
A plot could also revolve around Harry going back in time to the origin of the Master of Death legend. He discovers secrets about how the power was first created and used. Along the way, he meets his ancestors or other powerful wizards from the past. This could change his understanding of his own power and his role in the wizarding world.
Well, perhaps in the fanfiction, the Arcobaleno are intrigued by Harry's status as the Master of Death. They might seek his help to break a curse that is related to death in their world. Harry, in turn, could learn from the Arcobaleno's skills and powers, leading to an exchange of knowledge and a more complex, intertwined plot.
One idea could be that Harry Potter, as the Master of Death, somehow gets transported to the Ouran High School world. He could use his magical abilities in unique ways there, like using the Invisibility Cloak to play pranks on the Host Club. Maybe he'd also share his experiences with death and resurrection with the Ouran characters, leading to some deep philosophical discussions.
One idea could be that Harry, as the Master of Death, uses his new - found power to travel through different magical realms to learn ancient magic. He could meet long - lost magical creatures and gain their knowledge. Another plot could involve him using his power to bring back some of the good characters who died in the war, like Sirius or Lupin, but with unforeseen consequences that he has to deal with.
Another plot could involve a prophecy that foretells the union of the Master of Death and a powerful magician like Zatanna to save all of magic from a looming catastrophe. Harry and Zatanna have to overcome cultural differences in their magical practices as well as external forces that are trying to prevent them from fulfilling the prophecy. They face challenges like misunderstandings among other wizards and witches who fear the power they might gain if they succeed.
One idea could be exploring how Harry uses his newfound status as the Master of Death to bring back some of the characters who were lost in the war, like Sirius or Lupin. He could then form a new kind of magical order with them to safeguard the wizarding world in a different way.
One idea could be a competition among different wizards to claim the title of master of death in a more complex and dangerous magical arena. They might have to face challenges that test not only their magical skills but also their moral compasses.
One plot idea could be that Harry, as the Master of Death, has the ability to see the true nature of Voldemort's Horcruxes more clearly. He uses this knowledge to track them down in a more efficient way. For example, he can sense the presence of a Horcrux in a place where Voldemort has hidden it well, like an ancient, cursed forest. Another idea is that Harry can communicate with the dead in a more profound way as the Master of Death. He could get advice from the founders of Hogwarts on how to defeat Voldemort once and for all.
Another plot could revolve around the ghosts in the wizarding world and their connection to the aspect of death. Fanfiction could explore if they hold secrets about death that could be unlocked. For instance, Nearly Headless Nick might know something crucial about the afterlife related to the aspect of death that could help Harry in his journey.
One idea could be that the Goddess of Death has a special connection with Harry. For example, she might appear to him in a time of great danger and offer him a unique power that no one else has. This power could be related to seeing the true nature of dark magic, which would help him in his fight against Voldemort.