It could be an ancient shinobi who has mastered some kind of death - related jutsu and has ascended to a higher state of being. This shinobi might have been forgotten in the history of the ninja world.
The 'draught of living death' in HP fan fiction usually represents a sort of mystery and danger. It's a potion that has the power to make a person seem dead. Fanfic writers may play with this idea, perhaps having a character accidentally consume it and then the story revolves around the efforts of their friends to figure out what happened and revive them. It adds an element of suspense and intrigue to the story.
In some HP fan fictions, the 'draught of living death' is described as a shimmering, purple liquid with a thick consistency. It might give off a faint, sweet smell that is deceptively alluring.
The story of the sequel might involve the child of the Death Eater discovering hidden secrets about their family's past and trying to forge their own path in a world still wary of their heritage. There could be magical duels and unexpected alliances along the way.
You can start by looking on popular fanfiction websites such as Archive of Our Own. Use relevant search terms like 'HP master harem' to narrow down the results. Check the ratings and reviews of the stories to get an idea of their quality.
Another plot could be that the Death Eaters' child is sent on a mission by their parents, but during the mission, they witness the true cruelty of the Death Eaters. This makes them defect. They then have to flee from their family and the other Death Eaters. While on the run, they learn about the power of love and friendship from the people they meet, which gives them the strength to fight back against their former allies and try to make amends for the wrongs their family has done.
Typically, it involves a character or characters who have some sort of power or knowledge related to death. This could be the ability to cheat death, to control the dead, or to understand the afterlife.
The 'Merchant of Death' concept probably means that Tony is involved in activities related to death in a commercial way. For example, he might be selling things that can cause death, such as weapons or poisons.
One possible plot could be the child of a Death Eater trying to redeem the family name. Maybe they discover secrets about their parent's past actions during the wizarding war and strive to make amends in the wizarding community. They could face opposition from both those who still hold grudges against Death Eaters and those who want to keep the dark past buried.
There are many HP master harem fanfictions that center around Hermione Granger as well. In some, she might be in a group with other characters from different houses, like Slytherin and Hufflepuff, creating interesting dynamics. These stories often take the existing world of Harry Potter and expand on it with new plotlines based on the harem concept.