Who could be the main antagonist in 'dean becomes a dragon supernatural fanfiction'?

In this 'dean becomes a dragon supernatural fanfiction', it could start with Dean being in a fight with a powerful demon. During the battle, the demon casts a spell that backfires and instead of killing Dean, it turns him into a dragon. Dean then has to deal with the fact that he is no longer fully human. He may have to hide from other hunters who might see him as a threat. Meanwhile, he tries to figure out how to use his new dragon abilities to continue his fight against the supernatural, all while trying to find a way to turn back to his normal self.

The main antagonist could be an evil knight who has a vendetta against dragons. When the princess turns into a dragon, he sees her as a prime target and tries to slay her, believing all dragons are evil. He doesn't care that the princess was once human and is only focused on his own prejudiced views.

It could be a dark wizard who wants to capture Hedwig - as - a - dragon for her powerful new form. Maybe he wants to use her dragon abilities for his own evil plans.

Maybe an ancient dragon that has been awakened from its slumber and views Natsu as an intruder in the dragon world. Since Natsu is a new - made dragon, this old dragon might try to drive him out or even harm him.

It could be an evil dragon slayer who is jealous of Natsu's new form. This antagonist might try to steal Natsu's power or find a way to turn him back to his normal self out of envy.

It could be a dark wizard who wants to control the dragons for his own evil purposes. He might see Harry as a threat because Harry is forming a bond with the dragons and teaching them to resist dark magic.

There could be a group of pure - blood wizards who believe that dragons are beneath them and that Harry is tainting the wizarding world by associating with them. They would try to stop Harry from his dragon - related activities, and they might use underhanded tactics like casting spells on him or trying to get him expelled from Hogwarts.

Perhaps an evil mage who has been researching on how to control dragons. When he hears about Natsu's transformation, he sees Natsu as a perfect specimen to experiment on. So he becomes the main antagonist, trying to capture Natsu and use his powers for his own dark purposes.

Perhaps an ancient sorcerer who has the ability to control celestial dragons. He sees Lucy as an obstacle to his domination over the world using the power of these dragons. He would use his vast knowledge of magic and his control over the dragons to try and defeat her.

Another option is a rival dragon slayer who sees Natsu's transformation as a threat to his own status. This rival could try to stop Natsu from fully becoming a dragon or try to defeat him to prove his own superiority.