No. 'Harry Potter' is a completely original work with its own unique world, characters, and storylines created by J.K. Rowling. It has no relation to Grell Sutcliff fanfiction.
One great 'Grell Sutcliff x Reader' fanfiction is 'A Crimson Bond'. It beautifully captures Grell's flamboyant personality while creating a sweet and somewhat comical relationship with the reader. The author does an excellent job of writing in the Black Butler universe's style.
One common theme is his relationship with other characters, especially Sebastian. Their interactions, whether it's rivalry or an unexpected friendship, are often explored. Another theme is his own self - discovery. Grell is a complex character, and fan fictions often focus on him coming to terms with who he is, his desires and his place in the world.
One popular Grell Sutcliff OC fanfiction might be those that explore his relationships in new ways. For example, stories where his OC partner helps him navigate the complex world of the Black Butler universe. Another could be ones that focus on his backstory and how an OC could have been involved in his past.
Characterization is key. A good 'Grell Sutcliff x Reader' fanfiction should accurately portray Grell's over - the - top, passionate, and somewhat bloodthirsty nature. The reader - insert character also needs to be well - developed, with their own personality and reactions to Grell's antics.
There might be. The idea of Harry Potter being the son of Grell Sutcliff is an interesting and rather unusual crossover. Some fanfiction authors love to explore such unique concepts. Check on AO3 in particular, as it has a large and diverse collection of fanfictions. You could search using relevant tags like 'Harry Potter', 'Grell Sutcliff' and 'crossover' to narrow down the results.
One common theme is the exploration of Grell's unique personality. His flamboyant and passionate nature often plays a big part in the relationship with the reader. For example, in many fics, his love for the dramatic might lead to some comical or intense situations with the reader.
It's probably a misinformed idea. Maybe someone is confused or just making a baseless claim without proper knowledge of either 'Harry Potter' or Grell Sutcliff.
The lack of complete exploration of their relationship in the original source material is a big factor. Fans are left with a lot of room for imagination. So, they take it upon themselves to write fan - fictions that could be anything from comical adventures together to deep, emotional and angsty stories about their unrequited love or their shared secrets in the dark world of Black Butler.
You can start by looking on fan - fiction websites like Archive of Our Own (AO3). It has a large collection of fan - fictions, and you can simply search for 'Grell Sutcliff and Undertaker' in the search bar. Another option is FanFiction.net, which also has a good number of works related to various fandoms, including Black Butler where these characters are from.