If the familiar is something like a dragon, it could greatly impact the plot. Dragons are powerful and feared. The character with the dragon familiar might be constantly hunted by those who want to use the dragon for their own purposes or those who fear its power. This would create a lot of conflict and drive the story forward as the character has to protect their dragon and themselves.
When the familiar is an intelligent magical creature like a house - elf with special powers in fanfiction, it can change the plot entirely. The house - elf could use its magic to help or hinder the main character. For example, it could use its ability to apparate anywhere to spy on enemies or steal important items. This would create a complex web of relationships and events, as the main character has to manage this unpredictable and powerful familiar while also dealing with other challenges in the story.
An unusual familiar such as a thestral could have a profound effect on the plot. Thestrals are associated with death, so the character with a thestral familiar might be more in tune with the darker aspects of magic. They could be involved in uncovering secrets related to death or the afterlife. This would add a spooky and mysterious element to the story, leading the plot in directions that explore the unknown parts of the wizarding world.
The pet might cause trouble for Harry. Imagine it has a mischievous streak and keeps getting into places it shouldn't be, like the Slytherin common room. This would lead to all sorts of awkward and dangerous situations for Harry, forcing him to come up with creative solutions to get out of trouble.
I'm not sure specifically as there are many different fanfictions with this title. It could be about Harry Potter having a very strange or unexpected magical creature as his familiar, perhaps a creature from a different magical realm or one with unique powers.
The dark familiar can make Harry more cautious. For example, if it has a tendency to attract dark magic or dangerous situations, Harry has to be more aware of his surroundings. This forces him to grow in his ability to sense trouble.
One example could be a phoenix. In regular Harry Potter lore, only Dumbledore has a phoenix as a familiar. But in fanfiction, a character like Harry could have a phoenix as his unusual familiar. It could be a sign of his special connection to magic and his destiny, as phoenixes are symbols of rebirth and great power.
The demon wolf familiar could make Harry more confident. Since he has this unique and powerful companion, he feels more capable of taking on challenges. For example, when facing bullies like Draco Malfoy, the presence of the wolf gives Harry an extra sense of security, which in turn makes him stand up for himself more often.
In this fanfiction, Harry Potter is the central figure. His unusual familiar, which could be a creature that has never been seen in the wizarding world before, is also a main character. Additionally, the professors at Hogwarts, such as Dumbledore or Snape, could play important roles. Dumbledore might offer his wisdom regarding the familiar, while Snape could be initially distrustful. And of course, Harry's friends, they could be there to support him, offer advice, or get into some comical situations because of the unfamiliar nature of this new familiar.
It can create immediate conflict. If a young wizard performs magic accidentally, the Trace can bring the Ministry's attention, like in some fanfics where a minor character's small magic act sets off a chain of events because the Ministry gets involved.
The 'darkness' can make the plot more complex. It might introduce new challenges for the characters that they have to overcome. For example, if there are new dark spells or dark creatures in the fanfiction, the characters need to find ways to deal with them.
In some fanfictions, he might find it in the Forbidden Forest during one of his adventures. Maybe while exploring the deeper parts of the forest that are off - limits to most students, he stumbles upon a young pegasus in need of help. Harry, being the kind - hearted person he is, bonds with the pegasus and it becomes his familiar.
The concept of Harry as a pyromancer can change the fanfiction plot in many ways. Firstly, his battles would be different. He could use fire to his advantage, which might make him more of a force to be reckoned with. Secondly, his relationships with other characters could shift. Some might be jealous of his new power, while others could be more drawn to him. Also, it could introduce new elements to the overall story, like a search for the origin of his pyromancy powers or a need to control them better to avoid causing accidental destruction.