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.
The doggy could be a familiar of a new character in the fanfiction. This character could be an outcast or a secret wizard living near Hogwarts. The tub is where the doggy likes to hide when it senses danger. Harry Potter stumbles upon the tub and the doggy while exploring the Forbidden Forest. The doggy then leads Harry to its master, and together they form an alliance to face a common enemy, perhaps a group of rogue wizards who are causing chaos in the wizarding world.
He might be a character who was involved in the politics of the wizarding world. Fanfiction could explore how his influence, either positive or negative, affected the balance of power. And this could in turn impact the events that Harry has to face. For example, if Arcturus Black had made certain alliances, it could change the dynamics of the war against Voldemort.
Cassandra Black can fit in many ways. She could be a key figure in uncovering forgotten magic or prophecies. For example, she might have knowledge of an ancient spell that could help Harry defeat Voldemort.
Django could be a new student at Hogwarts who has some sort of special ability that comes from his non - magical background. For instance, his skills in marksmanship could translate into a unique form of spell - casting accuracy.
In fanfiction, gargoyles could be ancient magical beings that were created by a powerful wizard in the past. In the Harry Potter universe, they could hold the key to some long - forgotten magic. Harry Potter might stumble upon this when exploring the castle. They could be like living puzzles that Harry has to figure out in order to unlock their secrets and gain their help.
A priest could be a healer in the wizarding world. Just as priests in real life are often associated with providing spiritual and sometimes physical comfort, in the 'Harry Potter' universe, he could use his religious knowledge along with magic to heal the sick or injured wizards. For example, he might say prayers while using a spell to soothe a patient's mind and body.
Riolu can fit in as a magical creature. It could be a creature that has been hidden in the wizarding world for ages and is now discovered by a Hogwarts student. For instance, it might live in the Room of Requirement, which has all sorts of hidden things. The student could then form a bond with Riolu and they embark on adventures together.
Shukaku could be a powerful magical beast that has been sleeping deep within the grounds of Hogwarts for centuries. Only a very powerful spell or a unique combination of spells could awaken it. Once awakened, it could either be a great ally or a terrifying foe depending on how the wizarding community treats it.
She could be a powerful ally. Since Bella has enhanced physical abilities in her own story, in the Harry Potter universe, she could use those to help in battles. For instance, she could be part of the Order of the Phoenix and use her speed and strength to fight against Voldemort's forces.
It could be a new threat. For instance, it might be a creation of Voldemort's followers trying to spread terror among the wizards. It could have some special powers like the ability to make people hallucinate their worst fears just by looking at it.