Who could be the main antagonist in a Merlin as a Borrower Fanfiction?

A powerful dark wizard could be the main antagonist. He might be jealous of Merlin's natural magic abilities and the Philosopher's knowledge. He could try to disrupt their work, steal their research, or even harm them to further his own evil plans.

It could be an unknown sorcerer who has infiltrated Camelot. This sorcerer could sense Merlin's power during 'The Moment of Truth' and see him as a rival. So, he tries to frame Merlin for dark magic, causing chaos in Camelot and forcing Merlin to prove his true intentions while also dealing with this new threat.

Morgana could be a great antagonist. She might see the Lady of the Lake as a threat to her own power and plans for Camelot. And she could try to stop any alliance between Merlin and the Lady of the Lake.

Morgana could be a great antagonist. She might see Merlin's sister as a threat to her own plans for Camelot. Maybe she discovers that Merlin's sister has a power that could undermine her magic or her influence over the court.

Morgana could be the main antagonist. She might see Merlin's transformation as an opportunity to further her own plans. Since Merlin is in a more vulnerable state as a girl, Morgana could try to use this to her advantage, perhaps by trying to turn the court against Merlin or using her new form to manipulate her into doing things that would harm Camelot.

It could be Morgana. Since she was always at odds with Merlin and Camelot, his death wouldn't stop her from her plans. In fact, she might be emboldened by it. She could use the chaos that follows Merlin's death to her advantage, trying to take over Camelot more easily. Also, there could be some dark magic force that was previously held at bay by Merlin. Now that he's gone, this force could become the main antagonist. It could be something like an ancient evil that Merlin was constantly keeping in check, and without him, it starts to spread and cause destruction.

Maybe an anti - elf group within Camelot. They see the elven apprentice as a threat to the kingdom and will do anything to get rid of the apprentice. They could be led by a noble who has a deep - seated hatred for the elves and views the relationship between Merlin and the apprentice as a danger to Camelot's stability.

Perhaps a powerful and corrupted spirit that guards Merlin's Castle and sees Harry and his friends as intruders. This spirit might have its own evil agenda and try to stop Harry from achieving whatever goal he has in the castle, like obtaining a powerful artifact or knowledge. It could use all sorts of dark magic and illusions to deceive and harm them.

It could be Morgana. She might see Merlin's transformation into a dragon as a threat to her own power and plans. So, she tries to stop him from fully becoming a dragon or tries to use his new form for her own evil purposes.

One plot idea could be Merlin, as a borrower, is discovered by Arthur. At first, Arthur is shocked but then becomes intrigued. He decides to protect Merlin from the other humans in the castle. Another idea is that Merlin, in his tiny form, uses his magic in new and creative ways to help the borrowers' community. For example, he could create miniature tools or defenses against predators. A third idea might be that Merlin has to go on a quest to find a magical item that can restore his normal size, all while facing the challenges of being so small in a big world.