Another interesting storyline could be set in an alternate universe where Voldemort won the war. In this cold blood fanfic, the wizarding world is a desolate and cruel place. Harry Potter, instead of being the hero, has to survive in this new world order. He may have to adopt cold blooded strategies just to stay alive, like forming alliances with former enemies or using dark magic himself, which would be a huge moral dilemma for him.
There could be a midnight story where Harry accidentally travels back in time during a midnight stroll in the castle. He ends up in the time of the founders of Hogwarts. He has to interact with them without changing the future too much. This gives him new insights into magic and how Hogwarts was built, which he can use to strengthen the defenses of Hogwarts in his own time.
The unique combination of magic and vampires. In normal Harry Potter stories, there are no vampires like in True Blood. Fanfics bring these two elements together. It allows for new types of characters and relationships. For instance, a vampire attending Hogwarts would be a very different story.
In cold blood Harry Potter fanfics, Harry's personality might become more cynical. Instead of his usual hopeful and somewhat naive self, he could be distrustful of others. For example, he might suspect his friends of having ulterior motives more often.
In some Harry Potter fanfics, there are candies like 'Glowing Gumdrops' which are said to give off a soft light as you chew them. They're often used in magical games where the players have to find their way in the dark while chewing the gumdrops.
A really interesting 'Cold Blood' Harry Potter fanfic is the one where Harry, after being betrayed by someone close to him, turns cold - blooded in his pursuit of justice. He becomes more calculating and less impulsive, which completely changes the dynamics of his relationships with his friends and foes alike. This fanfic explores how his personality shift affects the overall plot of the wizarding world.
There are also fanfictions that focus on the backstories of minor characters. For instance, a story about Neville's parents before they were tortured into insanity. It could explore their time at Hogwarts, their relationships, and how they got involved in the fight against Voldemort. This gives a whole new perspective to the overall story.
Some fanfics might explore a storyline where the female Harry Potter as an omega mutant forms a special bond with other outcasts in the wizarding world. They could be other mutants or just those who are different in some way. Together, they could form a sort of resistance against the traditional norms of the wizarding society that discriminates against those who are not 'pure - blood' or 'normal'. This would be a story about friendship, acceptance, and fighting for equality.
The presence of Castiel makes it unique. Castiel is from a completely different fictional universe with his own set of powers and characteristics. When combined with Harry Potter's world, it creates a whole new set of story possibilities. For example, his angelic powers can interact with magic in unexpected ways.
The uniqueness of 'Harry Potter Druid Fanfic' lies in the cultural and magical blend. Druidism has its own rich history and mythology. When combined with the Harry Potter universe, it creates a really interesting mix. For instance, druids might have their own way of divination that is different from Trelawney's in the books. This can introduce new plot devices and character developments. Also, the druid characters can bring in their own set of magical tools and practices that are not part of the typical Hogwarts curriculum, making for a more diverse and engaging story.
The use of armbinders. In regular Harry Potter fanfics, you don't often see this element. It adds a whole new layer of mystery and magic. It can be used as a symbol, a tool for magic, or a part of a unique culture within the wizarding world in these fanfics.