Another possibility could be a new character introduced specifically for this fanfiction. This character could come from a different magical background or have a unique connection to the god - slayer magic. Maybe they are an outsider who stumbles upon the wizarding world and brings with them the knowledge or potential to use this powerful magic. This would add a fresh perspective to the story and allow for new storylines that are not as tied to the existing Harry Potter characters.
Hermione Granger could also be a great choice as the main character. She is extremely intelligent and studious. In a fanfiction with god - slayer magic, she could be the one to discover and decipher the secrets of this new form of magic. She might use her knowledge to not only master it but also to teach others and lead the fight against any god - related danger.
Hermione could also be a great main character. With her thirst for knowledge, she could be the one to stumble upon the secrets of Phoenix Slayer magic. She would then use her intelligence to master it and perhaps teach it to her friends to help in their battles.
It could be a new student at Hogwarts who has the powers of a Lightning Devil Slayer. This character would be an outcast at first, not fitting in with the normal wizarding students. But as the story progresses, they use their unique abilities to save the day, for example, during a battle against a horde of Dementors where their lightning - based powers are especially effective.
A Muggle - born blacksmith who discovers the wizarding world and uses his Muggle skills combined with magic he learns to create unique magical items. He could be the main character, struggling to fit in the wizarding world while also making a name for himself as a great magic blacksmith.
It could be another powerful mage who is jealous of Natsu's new war god slayer magic and wants to steal it for himself. This mage might have been researching ways to gain such powerful magic for a long time and sees Natsu as an obstacle to his own plans.
A young orphan who was raised by a hermit in the mountains and discovers they have the mountain dragon slayer magic. They are initially naive but grow into a powerful slayer through their adventures.
It could be a new character. Maybe a young wizard or witch who has a special connection to the God of Destruction. They could be from a long - lost magical family that has some ancient knowledge about this being. This character would then have to navigate the dangerous world of the Harry Potter universe, dealing with both Voldemort's followers and the chaos brought by the God of Destruction.
Hermione might be the main character. Since she is so studious and inquisitive, she could be the one to uncover the secrets of the God of the Sun in the fanfiction. She would then use her knowledge to help the wizarding world in a new way, perhaps by using the sun - related magic to combat dark forces.
Sasuke would also make a great main character. Given his affinity for lightning - based jutsus, he could be drawn to the Lightning God Slayer powers. He might see it as a way to become even more powerful and seek revenge on his enemies. His journey to master these powers could be filled with self - discovery and moral dilemmas.
One interesting concept could be the combination of the Harry Potter magic system with the idea of god - slaying magic. It might introduce new spells or powers that are specifically designed for taking on powerful, god - like entities. This could lead to really intense battles and power - up moments for the characters.
In this fanfiction, a main antagonist could be a powerful dark witch who has the ability to summon and control hordes of monsters. She believes that the wizarding world has become too soft and that only through chaos and fear brought by the monsters can it be purified. Harry, as the Monster Slayer, is her biggest obstacle. Another antagonist could be a group of Death Eaters who have discovered a way to use monsters as weapons in the post - Voldemort era. They want to continue the dark legacy and see Harry as the one who will always stand in their way. Also, a mysterious figure from the past, a forgotten dark wizard who has been locked away for centuries but is now free and is using monsters to exact his revenge on the modern wizarding world.