In the Black Butler universe, it could be through some sort of dark magic spell. He might have found an ancient grimoire that contains the incantation and the necessary ritual to call upon a reaper. For example, it could involve using specific ingredients like rare herbs, a drop of his own blood, and chanting the spell at a particular time, like midnight when the veil between the living and the dead is thinnest.
He could be using a magical artifact that has the power to open a portal to the reaper realm. This artifact might have been passed down in his family or he stumbled upon it by chance. To activate it, he might need to perform a series of complex actions such as arranging certain symbols in a specific pattern around the artifact and then uttering a special invocation. The reaper would then be drawn through the portal created by the artifact.
The consequences could be dire. Reapers in the Black Butler universe are not to be trifled with. They are tasked with collecting souls and maintaining the balance of life and death. Summoning one might disrupt that balance. For example, the reaper may take more souls than intended in the area as a result of being summoned, causing chaos among the living. It could also lead to the summoner, Harry in this case, getting into trouble with other supernatural entities who don't want the natural order meddled with.
Sure. In fanfiction, anything is possible. If we consider the idea of Harry Potter as a reaper in the Black Butler world, it could open up a lot of interesting plotlines. For example, his Hogwarts training in magic could interact with the reaper's duties in the Black Butler world. Also, his relationships with other characters from the Potterverse could be re - imagined in the context of Black Butler.
In some fanfictions, it could be through powerful magic spells that he discovers or is taught. Maybe he stumbles upon an ancient spell in the restricted section of the library that allows him to summon a family member. Another possibility is that he unknowingly activates some kind of magical artifact that has the power to bring a sister into his life.
One great 'Black Butler Demon Reaper Fanfiction' is 'The Reaper's Bond'. It delves deep into the relationship between the demon and the reaper in a very interesting way. The story has a unique plot that shows how they might interact beyond what we see in the original series. The characters are well - developed and their dialogues are engaging.
The magic system. Harry's magical abilities from the Potter series would be very interesting to see in the context of the Black Butler world. Maybe his spells could be used in new and unexpected ways when dealing with the tasks that reapers have.
One possible plot could be that the Reaper has come to collect a soul in Hogwarts, and Harry and Hermione, being the brave ones, try to stop it. They might discover that the Reaper is not all - evil as they thought and there could be some dark magic involved that they need to deal with together.
There's also a fanfiction where a female Grim Reaper is sent to observe the events in the Black Butler universe as a sort of undercover mission. It shows her perspective on the strange and often dark world of Black Butler. The story delves deep into her character, exploring her backstory as a Grim Reaper and how it shapes her actions in this new environment. It's really engaging as it combines the two concepts in a very natural way.
One common theme is mortality. Since Grim Reapers are associated with death, fanfictions often explore the concept of life and death, like how characters face their own mortality or how the Grim Reapers view the lives they are meant to end.
William T. Spears is also quite popular. His strict and no - nonsense attitude provides a great contrast to other more chaotic characters, and fanfiction often plays with his interactions with other reapers or the main Black Butler characters.
The Grim Reaper in Harry Potter fanfiction is really interesting. Fanfic authors often take the concept of the Grim Reaper from general mythology and blend it with the magical world of Harry Potter. It can be a force that is not fully understood by the wizards. It might be connected to the Forbidden Forest, as that place already has an air of mystery and danger. The Grim Reaper could be seen as a part of the natural order of things in this fan - made universe, and its presence could change the way the characters view life and death.