Who could be the main antagonist in a 'Harry Potter Ultra Instinct Fanfiction'?

It could be a rogue ninja who has also discovered a dark version of the ultra instinct. This ninja uses his power for evil, like taking over villages and enslaving people. He would be a major threat to Naruto and his friends because his power is so similar yet so different from Naruto's ultra instinct - like powers.

Maybe it could be a new dark wizard or witch who has a unique power that confounds Harry's rational thinking. This antagonist could be someone who uses mind - games and illusions, making it difficult for Harry to use his normal knowledge to fight back. So, he has to rely on his instincts more than ever to figure out their true intentions and defeat them.

Another possibility is a rogue Saiyan from an alternate timeline. This Saiyan could be jealous of Goku's status as the strongest Saiyan in his own timeline. So, they use time travel to come to Goku's timeline and try to defeat him and take over as the dominant Saiyan.

One idea could be Harry discovers he has an ultra instinct ability during a life - threatening battle with Voldemort. This new power allows him to anticipate Voldemort's every move and counter it with ease. It could be a power that is awakened when he is in extreme danger and has to protect his friends and Hogwarts.

It could be a long - lost Uchiha clan member who has a killer instinct amplified by a dark jutsu. This character has a vendetta against the Hidden Leaf for past wrongs done to the Uchiha. They use their Sharingan in very cruel ways, not hesitating to kill even innocent bystanders to achieve their goals.

Perhaps a long - lost relative of the Potter family who feels they were unjustly excluded from inheriting the manor. This relative could be jealous of Harry's status and the wealth associated with the manor. They might use dark magic to try and claim what they think is rightfully theirs, leading to a battle of magic and loyalty within the Potter family and among Harry's friends.

In this Ultra Instinct Batman fanfiction, there could be a moment where Batman has to teach others how to access a similar state. Maybe he trains Robin or some of the other young heroes in Gotham. This would not only show his growth as a character but also how he is able to pass on his knowledge and skills. It could also lead to the formation of a new and more powerful team in Gotham to fight against the ever - increasing threats.

A new dark wizard or witch could be created specifically for this fanfiction. This character could be interested in using the Huntsman's skills for their own evil purposes. If the Huntsman refuses, they become enemies. This antagonist could have powers related to dark forest magic, something that the Huntsman is familiar with but in a more malevolent form.

Voldemort could still be the main antagonist. Even if Demetri has some sort of connection or change in the fanfiction, Voldemort's overarching evil plans would still be a major threat to both Harry and Demetri, especially if Demetri tries to deviate from the Death Eaters' path.

The minotaur itself could be the main antagonist. It's a powerful and dangerous creature, and if it's been set loose in Hogwarts or is guarding something that Harry needs, it would be a major obstacle for him to overcome.