It could be an angry minor god. Maybe a god who has always been overshadowed by the big three and decides to get revenge. This god, using some dark magic they've been secretly studying, turns the big three into animals.
Well, one possibility could be that they are turned into animals as a form of punishment. For example, Zeus could be turned into a peacock, Poseidon into a seahorse, and Hades into a black dog. Then they have to figure out how to reverse the spell while dealing with the challenges of being in animal forms, like Zeus having to deal with not being able to fly as high as he used to in his peacock form and facing threats from other animals.
Maybe it's an accidental spell gone wrong. A well - meaning wizard or magic user was trying to do something else, but the spell misfired and turned Percy into a baby. In this case, they would then be on a mission to reverse the spell.
The headmaster, Dumbledore, could also be the one to discipline Hermione. He has the overall authority in Hogwarts. If Hermione's actions endanger the safety of the school or other students in some way in the fanfiction world, Dumbledore could step in with a form of discipline, perhaps by restricting her access to certain areas of the school for a while.
It could be someone with malicious intent, like a criminal or an abuser.
Another possibility is that it's a rogue Shadowhunter. There are always those in the community who don't agree with the way things are going. If Clary's actions or ideas are seen as too radical, this rogue Shadowhunter might try to stop her by injuring her. This could also lead to a story about Clary trying to understand the motives of this attacker and potentially reform them.
It could be Orochimaru. He was always interested in powerful jutsu and having Naruto, who is the Jinchuriki of the Nine - Tails, under his control would be a great asset. He might have planned a secret mission to snatch Naruto at birth for his experiments.
The following factors needed to be considered when grasping the protagonist's personality: 1. The protagonist's background and experience: The protagonist's personality will be influenced by his unique background and experience. For example, a child born in a noble family might be more elegant and arrogant, while a child born in poverty might be more tenacious and brave. 2. The main character's goals and motives: The main character's personality will also be affected by his goals and motives. For example, a protagonist who acted for revenge might be more sinister and cunning, while a protagonist who worked hard to realize his dreams might be more positive and optimistic. 3. The protagonist's opponents and enemies: The protagonist's character will also be affected by his opponents and enemies. A kind and benevolent protagonist's opponents and enemies might be more cruel and evil, thus creating a more complicated and profound character. 4. The protagonist's personality changes: The protagonist's personality will change due to his unique experiences and goals. For example, a cheerful and optimistic protagonist might become silent and withdrawn after experiencing certain events, while a cold and heartless protagonist might become kind and benevolent after experiencing certain events. Therefore, to grasp the character of the protagonist, one needed to consider the above factors and create a character with depth and complexity in different ways.
It could be Sasuke. Maybe after realizing how much the village and the world needed Naruto, Sasuke found a way to bring him back. He might have searched through ancient scrolls or sought help from some reclusive ninjas who knew about the resurrection jutsu.
It could be an old enemy from Percy's past, like Kronos. Even though he was defeated, there could be a remnant of his power or a follower who wants to take revenge on Percy by making him disappear. Kronos always had a strong hatred for the demigods, especially Percy.
It could be an evil magician. They might see Sadie as a threat to their plans, so they try to take her out by attacking her. For example, they could use dark magic to send shadowy creatures after her that would harm her.