What could be the plot of 'Harry Potter awakens the devil gene fanfiction'?

It could be Voldemort still. Since Harry has awakened the devil gene, Voldemort might see this as an opportunity to either corrupt Harry further or use his new power for his own dark purposes. So he would be the main force against Harry.

In this fanfiction, it could be that the appearance of the keyblade is a sign of a greater prophecy. Harry, being the chosen one in his own world, is now also the one to awaken the keyblade. He has to face challenges like learning new combat styles, understanding the keyblade's magic which is different from his usual spells. And along the way, he might make new friends or enemies related to the keyblade's origin and purpose.

Well, he could start by trying to find a way back to his own world. But in the process, he gets involved in the affairs of Spira. He might meet some characters who are similar to his friends at Hogwarts. They could form a group and together they explore the mysteries of Spira. Harry could also share his knowledge of magic with the local wizards (if there are any), and in return, learn about the unique magic system of Spira.

One possible plot could be that Harry Potter, while exploring new magical realms, stumbles upon a portal that leads him to the Star Wars universe. There, he meets Rey and they discover that magic and the Force have some similarities. They could team up to fight against a new dark force that is threatening both their worlds.

The Devil Gene could be integrated as a new form of magic that has been hidden for centuries. A character might discover it accidentally and start to explore its powers, which could lead to new adventures and challenges.

Another concept could be a conflict between those with the Devil Gene and the traditional wizarding society. The Devil Gene might be seen as something dark and dangerous, so there could be a lot of prejudice and attempts to control or eliminate those who possess it. This could create a really tense and interesting story dynamic.

Well, perhaps Harry Potter discovers some ancient magic related to the Jagan in this fanfiction. Maybe he has to face new and powerful enemies as a result of awakening it.

One possible interesting plot could be a crossover where the characters from Harry Potter world encounter the Lightning Devil Slayer. Maybe the Devil Slayer's powers are mistaken for dark magic in the wizarding world at first. Then, they realize that they can work together to fight a common enemy, like a new dark force that combines the elements of the dark arts and the devils the slayer usually faces.

A great plot for this fanfiction could be that the magic from the Harry Potter world is actually an ancient form of the Force that has been forgotten in the 'Star Wars' universe. So, a group of wizards and witches from Hogwarts, led by Ron Weasley, travel to the 'Star Wars' galaxy to teach them about magic. However, they soon find out that the Dark Side of the Force is very similar to the Dark Arts in their world, and they have to fight against it together with the Jedi and the Resistance. This would bring a whole new dynamic to both universes.

A new character from the Kingdom Hearts universe could be the main antagonist. Maybe a powerful Heartless or a dark Keyblade wielder who sees Harry as a threat since he has awakened the keyblade. This antagonist could be after Harry to take the keyblade for their own evil plans.