A theme could be redemption. Maybe Harry, through his relationship with Death, is seeking to redeem something in the wizarding world or in his own past. It could also be about sacrifice. Given the nature of Death, Harry might have to make great sacrifices in this fanfic concept. Also, there could be a theme of mystery, as Death is such an enigma in the series, and this relationship would surely be full of mystery.
One possible theme could be the exploration of life and death. Since Harry is marrying Death, it might delve into the deeper meaning of mortality and how it relates to the magical world. Another theme could be power. Death in the Harry Potter universe has a certain power, and this could be explored in the relationship with Harry.
One big challenge could be public opinion. The wizarding community has a long - held grudge against Death Eaters. So Harry would face a lot of criticism and distrust from the public. People might think he's gone to the dark side or that he's being naive.
One possible plotline could be that Harry, being a wizard from the magical world of Harry Potter, somehow gets involved with the dark and supernatural world of Hellsing. His magical abilities might be a source of both intrigue and conflict. Maybe he uses his magic to help the Hellsing organization in their fight against vampires and other dark creatures, and during this process, he falls in love with a character from Hellsing and they get married.
Another theme might be the challenges of a new relationship. In a 'bill marries mabel fanfic', they would face various challenges, like dealing with each other's families or friends. And this could be a major theme as they navigate through these difficulties together. For example, if Bill has a different social circle than Mabel, how do they handle the integration? Also, cultural differences if applicable in their fictional setting could be explored.
One possible theme is the clash of cultures. Harry comes from a world of magic hidden from muggles, and the princess from a more traditional monarchy - based world. Their union would involve dealing with the differences in their upbringing, values, and social norms.
One possible plot could be that after Cedric survives the Triwizard Tournament, he and Harry grow closer over time. They start to bond over shared experiences at Hogwarts, like their mutual dislike for Umbridge. Their friendship gradually turns into love, and they decide to get married in a small, private ceremony with their closest friends and family from the wizarding world.
One common theme is the exploration of polyamorous relationships. Since Harry is marrying two people, it delves into how such a relationship can work in the context of the Harry Potter world. Another theme could be the challenges they face from the wizarding society which might not be fully accepting of such a relationship at first.
Well, a common theme is the reimagining of the wizarding world with them as a couple. It could involve how they would raise their children in terms of magic education and values. Also, there is often the theme of them facing threats that were not in the original story but are now relevant because of their relationship status. For example, new dark wizards might target them as a powerful couple.
Well, it could involve a plot where the wizarding world discovers Harry's immunity and tries to either use it for their own gain or tries to figure out how it happened. There could be a race between the good and the bad characters to unlock the secret of his immunity. Maybe Harry has to go on a journey to understand this strange new power within him, and along the way, he meets new allies and enemies.
Another theme is the exploration of life and death. These fanfics often look at the boundaries between the two. They might show Harry having the ability to see the souls of the dead, or being able to influence the passage of souls. It gives a different perspective on the afterlife in the Harry Potter universe.
One possible theme could be sacrifice. Maybe Twilight Sparkle sacrifices herself to save her friends or Equestria. Another theme might be dealing with grief among the other ponies after her death.