In some versions, the Goddess of Death could be a reincarnation of an ancient witch who was wrongly persecuted in the past. She has returned as a more powerful being with the ability to control death itself. Harry, being the chosen one, is the only one she can communicate with. She shares with him the secrets of defeating death, not just in the form of Voldemort, but also in the way wizards have always feared it.
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.
Perhaps the Goddess of Death is an ancient being that has been observing the wizarding world for centuries. In the fanfiction, she decides to interfere when she realizes that the balance between life and death is being severely disrupted by Voldemort's actions. She could then guide Harry and his friends in a series of quests to restore this balance.
One idea could be that Fem Harry, as the Goddess of Death, has the power to see the final moments of every being. She uses this to prevent unjust deaths in the wizarding world. For example, she might foresee a student being wrongly accused and killed by a dark wizard and intervenes just in time. Another plot could involve her dealing with the afterlife. Maybe she discovers that some souls are being trapped and tortured by dark magic in the in - between realm, and she has to fight against the dark forces there to free them.
Another plot could be that a powerful American dark wizard is using death as a weapon. He's creating an army of the undead or something similar. Harry, along with his friends Hermione and Ron (if they accompany him to America), has to find a way to stop this wizard. They might encounter unique American magical creatures that are either helping or hindering their mission. The story could explore the cultural differences between the American and British wizarding communities in the face of such a great threat.
Perhaps in the fanfiction, the God of Death has a plan for Harry that involves not just his survival but also a complete transformation of the wizarding world. This could lead to Harry having to make some really tough choices between following the God of Death's plan and staying true to his friends and the values he has always held.
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 death goddess has the power to bring back characters from the dead in the Naruto universe, but at a great cost. Maybe she offers Naruto this chance to revive his parents, but in return, he has to sacrifice some of his own chakra forever.
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.
Maybe the Eyes of Death are actually the eyes of a long - forgotten magical creature. In the fanfiction, this creature has a connection to Harry's past, perhaps his family. Harry has to figure out how to communicate with the creature through its eyes to gain its power and use it against the Dark forces.
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.
Another plot idea is that Fem Death has a connection to Harry's parents. She might have made a deal with them long ago to ensure Harry's safety. In the fanfiction, Harry discovers this connection and has to navigate the implications of it. This could involve him having to make sacrifices or face challenges that test his loyalty and his understanding of his family's past.