It could be an evil wizard. The wizard might view the chibi as an abomination because it's a cute and innocent thing in a world full of darkness and he wants to rid the world of it. So he sets out to destroy the chibi, with Deadpool standing in his way.
Maybe it could be a mad scientist who wants to study the chibi. He sees it as a unique specimen and is willing to do anything to get his hands on it.
The main antagonist could be a scientist who wants to study the chibi. This scientist might be a bit of a madman, seeing the chibi as a unique specimen to experiment on and not caring about its well - being. He could try to capture the chibi and Peter has to stop him.
Well, the plot could involve Deadpool being really confused at first when he gets this chibi sidekick or something. Maybe the chibi is a super - powered being but in a really cute form. And Deadpool has to protect it from some bad guys who want to use its power for evil.
Any fan who loves the character Peter and has an interest in chibi characters could write it. It could be a young writer who is just starting out and wants to explore the concept of a character getting a cute, little companion.
Deadpool himself could be considered the main antagonist in this case, as he is the one who is set on killing Peter Parker. His unpredictable and violent nature makes him a formidable foe.
Another option is a group of anti - magic fanatics. They view Percy's wings as an abomination because they are a result of magic. They hunt Percy down, believing that by getting rid of him and his wings, they are protecting the world from the 'evils' of magic.
It could still be Hawk Moth. Since Nathalie has been working with him, getting a Miraculous might make her a threat to his plans, so he could turn against her and become the main antagonist.
It could be a long - lost relative of an old enemy. For example, if there was a powerful dark wizard that Natsu defeated in the past, this relative might come seeking revenge and be powerful enough to kill Natsu.
Maybe an evil artist from another dimension. This artist is jealous of Nathanael's pure creativity and the unique power of his miraculous. They come to Nathanael's world to steal his ideas and use his miraculous for their own dark purposes, like creating chaos and destruction through art.
Maybe the main antagonist is an old enemy of Robin's who becomes jealous of his new powers. This enemy then devises a plan to steal Robin's powers or at least neutralize them so that he can regain his former status as the top threat. He could be a powerful martial artist or a criminal mastermind with a large network of henchmen.
It could be a jealous rival. This rival might be envious of mankae's popularity or achievements. So, they set him up to get arrested by providing false information to the police. They want to see mankae's downfall and think that getting him arrested is the best way to achieve this.