In some fanfictions, the Black Shuck could be a guardian of a hidden magical artifact. It's a fearsome beast that wards off those unworthy of approaching the powerful item. Maybe it has a connection to an ancient wizarding family, and only a descendant of that family can communicate with it or pass by it without being attacked.
Another way is that the Black Shuck is a manifestation of an ancient magic that has been long forgotten. A group of students in the fanfiction could discover some old texts about it and decide to investigate. As they dig deeper, they find out that this Black Shuck is connected to a much larger mystery that could change the way they view the history and magic of the wizarding world.
In some pitch - black Harry Potter fanfictions, there might be a storyline where Voldemort actually had a valid reason for his actions, at least from a certain perspective. It could explore how the wizarding society's discrimination and power - hungry nature drove him to the dark side, and Harry has to grapple with this new understanding. Also, a story could involve Harry being corrupted by the power he holds, turning him into a much darker character than we know from the original books.
The plot where Murtagh teaches Harry some of his unique magic techniques is really cool. It shows how different magical systems can interact. For example, in a fanfic I read, Murtagh showed Harry how to use a spell that was common in his world but unheard of in Hogwarts.
Perhaps a storyline where Fem Harry discovers a connection between the magic in the Harry Potter world and the arcane powers in Warhammer. She could then embark on a journey to understand this connection better, facing challenges along the way. She might meet characters from both universes who either help or hinder her in this quest, making for a very engaging fanfiction.
One of the most interesting plots could be Snape having to protect Harry in a very unexpected way. For example, in a fanfic where dark magic has been unleashed in a different form and it targets Harry specifically. Snape, despite his initial reluctance, realizes that Harry is the key to stopping it and has to put aside their differences. Another plot could involve Snape and Harry being transported to an alternate magical realm where they have to rely on each other to survive. They slowly start to understand each other's past traumas and develop a grudging respect. A third plot might be that Snape discovers a long - lost prophecy about Harry that changes his perception of him completely and he becomes his secret mentor in a much more involved way than in the original books.
In some fanfics, the plot might involve Harry using his snake form to spy on the Death Eaters. For example, he could slither into their secret meetings undetected. Another interesting plot could be that his snake form is somehow connected to Salazar Slytherin. Maybe he discovers that his ability to turn into a snake is part of an ancient bloodline magic.
A common plot in 'Harry Potter Dolores Umbridge Fanfiction' is her getting a taste of her own medicine. For example, in some stories, she is put through the same strict and cruel rules she imposes on others. It's a satisfying plot for those who dislike her character in the original books.
There are also fanfictions that look at Helena Ravenclaw from the perspective of her motherly love for Hogwarts. She's like a protective spirit in these stories, and the plot might involve her guiding certain characters, like Harry or Hermione, through difficult times at Hogwarts. It's a heartwarming and different take on her character that shows her connection to the school in a more emotional way.
Well, in some fanfics, like 'The Darker Side of Redemption', Lucius is given a chance at redemption after the fall of Voldemort. Harry plays a key role in this process, either by being a reluctant helper or an unexpected friend. The plot often involves exploring the darker parts of the wizarding world that were not fully shown in the original books.
One of the most interesting storylines could be a dragon handler who discovers a new breed of dragon in the Forbidden Forest. This could lead to a whole adventure of trying to keep it a secret from the Ministry of Magic while also learning about its unique abilities. Another could be a dragon handler who has to deal with a dragon that has been poisoned, and they have to find a cure using their knowledge of both magic and dragon physiology. Maybe a dragon handler who forms a special bond with a dragon and uses that bond to help in the war against Voldemort, like using the dragon to transport crucial supplies or even fight in battles.