One interesting concept could be the unique magic systems that students might learn in Goode Academy in fanfiction. For example, a new type of spellcasting that's not in the original source.
One interesting concept could be the unique power dynamics within the academy setting. For example, how different characters navigate between being a'slave' in some sense and still trying to achieve their academic goals. Another concept might be the relationships that form, whether they are friendships or something more complex, as the characters are dealing with this unusual system. And also, the idea of how the academy's rules and hierarchies are shaped by the slave - like elements.
The mysterious teacher characters can also be popular. In fanfiction, they might have a more complex backstory. For instance, a teacher who was once a great adventurer before coming to teach at the academy.
One interesting concept is alternate timelines. Fanfic often explores what would happen if the events in the show took a different turn in different timelines. For example, a character might not have their powers, which would completely change the story's dynamic.
Well, a cool plot might involve Percy's old enemies from the demigod world somehow influencing events at Goode. For example, a spell is cast that makes the students act like the minions of an ancient Greek villain. Percy then has to figure out how to break the spell without revealing his powers too much. Also, it could be interesting if there was a plot where Percy discovers a hidden part of Goode that has a connection to the gods, like a secret chamber that was built long ago by a demigod who attended the school.
A really interesting plot would be if Percy's friends from Camp Half - Blood transfer to Goode High for some reason. They all have to adapt to the mortal school life while also dealing with the threats that follow Percy, like a vengeful demigod from an enemy camp who wants to expose Percy in the middle of his mortal school life.
Another concept might be alternate universes. Maybe a Zootopia where predators and prey have completely different social dynamics. They could be living in a more equal yet chaotic world where the roles are not as clearly defined as in the original movie.
Well, in prey fanfiction, a cool concept is the creation of new powers or abilities for the characters. For example, the protagonist could gain some sort of psychic ability related to the alien technology. Some fanfics also delve into the idea of different endings to the Prey story, like a more positive or more tragic end compared to the original. And then there's the concept of crossovers, where Prey characters interact with characters from other science - fiction universes.
In ppg fanfiction, a cool concept is the idea of the Powerpuff Girls forming alliances with other characters from different shows or universes. This could lead to some really exciting crossovers and new storylines. Also, some fanfictions might focus on the origin story of the villains in the Powerpuff Girls world, like how Mojo Jojo became the way he is. And there could be fanfictions that explore the relationship between the Powerpuff Girls and their creator, Professor Utonium, in more depth, like how they feel about being created in a lab.
One interesting concept could be exploring the moral dilemmas that characters face during the purge. For example, a character might have to decide whether to save a stranger or protect their own family. Another concept could be how different social classes experience the purge. The rich might have more resources to protect themselves, while the poor are more vulnerable.
One interesting concept could be alternate universes where the slendytubbies have different powers or characteristics. For example, they might be able to communicate with humans in a friendly way instead of being menacing.