A group of vampire hunters who have gone too far could be villains. They start to target Nightwing, thinking he's a full - blown vampire and a danger to the city. They use extreme and unethical methods, which Nightwing has to fight against while also dealing with his own vampire - related issues. There could also be a vampire scientist who is creating new and more dangerous types of vampires and Nightwing has to stop his experiments.
An ancient vampire queen could be a formidable villain. She might be attracted to Nightwing's strength and determination and wants to turn him into her eternal consort. If he refuses, she'll stop at nothing to make his life miserable. She could also have a horde of loyal vampire minions that Nightwing has to battle through.
The classic Dracula could be a great villain. He could see Nightwing as a new and interesting prey or a threat to his plans in Gotham. Another option could be a vampire lord who wants to take over Gotham and sees Nightwing as the main obstacle.
Deathstroke is always a formidable foe. He has a history with both Batman and Nightwing. His skills as a mercenary and assassin could lead to some intense battles and strategic cat - and - mouse games in the fanfiction.
Well, villains in fanfiction about Nightwing could be drawn to it because it gives them a different kind of spotlight. Instead of just being the 'bad guys' in the main DC universe, in fanfiction, they can be more nuanced. They might find the interpretations of themselves in relation to Nightwing interesting. Also, Nightwing's popularity means that any story involving him, even from a villain's perspective, is likely to be read and discussed, which could be appealing to the villainous characters in these fan - created stories.
Deathstroke is a major villain. He is a highly skilled assassin and often clashes with Nightwing. His military - like tactics and combat skills make him a formidable foe for Nightwing.
One common theme could be the idea of redemption. Maybe the villain starts to see Nightwing's way of doing things and is influenced towards a more positive path. Another theme might be the battle of wits between the villain and Nightwing. Since Nightwing is known for his intelligence, villains in the fanfiction would want to match wits with him.
Batman could be a main character. Since Nightwing was trained by Batman, in a baby Nightwing fanfiction, Batman could be the one taking care of him, teaching him basic skills, and protecting him from the threats of Gotham.
Dr. Eggman could still be a major villain. He might see Sonic's new vampire state as an opportunity to study and use it for his own evil plans. Maybe he tries to create an army of vampire robots. Another potential villain could be an ancient vampire lord who sees Sonic as a threat to his rule over the vampire world.
A villain with an ice - based quirk could be a great antagonist. The contrast between Izuku's fiery Phoenix quirk and the ice - based powers would create interesting battle dynamics. The villain could be constantly trying to freeze Izuku and put out his phoenix flames.
Another possibility is that it's a group of mercenaries hired by a powerful underworld figure. The figure might want Nightwing out of the way so they can carry out their illegal activities more easily. The mercenaries would be well - trained and equipped, making it a difficult situation for Nightwing to escape from.
He might try to reason with kaldur. If Nightwing can make kaldur see that what he's doing is wrong or that there are better ways to achieve his goals, kaldur could let him go. Nightwing is known for his charisma and intelligence in such situations.
The Nightsisters could make great villains. They have their own dark magic and could be after Starkiller for some reason, like wanting to use his power for their own dark rituals.