Perhaps a story where a character reacts to the dangerous creatures in Amphibia. They initially fear them but then learn to co - exist with them. This could involve a lot of character development as they overcome their fears and discover the true nature of the creatures, which might not be as menacing as they first seemed.
Give your character a clear backstory. If they are from our world reacting to Amphibia, explain what led them to this new world. Maybe they were drawn by a mysterious force because they have a connection to Amphibia in a past life. This backstory will influence their reactions and decisions throughout the fanfiction.
Well, for amphibia crossover fanfiction, you could do a crossover with "Rick and Morty". Rick could build some sort of portal device that accidentally sends Morty to Amphibia, and then he has to rescue him. Or a crossover with "Ninjago". The ninja could come to Amphibia and use their martial arts skills to help out. Another option is a crossover with "Regular Show". Mordecai and Rigby could end up in Amphibia and their lazy and comical ways would contrast with the more serious Amphibia characters.
One idea could be a trainer's reaction when they encounter a shiny pokemon for the first time. Maybe they freeze in shock and disbelief at their amazing luck.
There are Amphibia OC fanfictions where the OC is a lost traveler from a far - off land. In these stories, the OC often has unique abilities or knowledge that either helps or hinders their journey in Amphibia. Some might involve the OC teaming up with Anne, Sprig, and the others to uncover secrets about Amphibia that were previously unknown, like hidden ancient ruins or the true origin of the Calamity Box.
One interesting plot idea could be Iron Man reacting to an alternate version of himself from a parallel universe. Maybe this other Iron Man has different tech or a different moral code, and the real Iron Man has to decide how to deal with this new version of himself.
One popular Amphibia fanfic could be those that explore the backstories of the main characters in more depth. For example, a fanfic might focus on Marcy's life before coming to Amphibia and how her love for games influenced her actions. Another type could be adventure - based fanfics, where the characters embark on new quests not shown in the original series.
Maybe the ghost roommates react to a modern technology being brought into the house. For example, a new smart TV that starts acting strangely in their presence. They could be both frightened and intrigued by it. They might try to figure out how to interact with it, which could lead to some comical situations as they don't understand how modern electronics work.
Another plot idea could be Spider - Man's reaction to a new piece of tech that falls into the wrong hands. He has to quickly figure out how to retrieve it and stop the bad guys from using it for evil. His thoughts and actions during this high - stakes situation would be great to read about.
In a Transformers War for Cybertron reaction fanfiction, a cool plot could be the reaction of the Transformers when they encounter an ancient and powerful entity from Cybertron's past. This entity could have the power to either end the war or make it even more chaotic. The Autobots might be more cautious and diplomatic in their approach, while the Decepticons would likely be more aggressive, seeing it as a tool for their own gain. Additionally, the reaction of different factions within the Autobots and Decepticons, like the scientists or the warriors, to this new development can create interesting sub - plots and character dynamics.
One interesting plot idea could be a character who is new to the Smash Bros universe and their reaction to meeting all the iconic characters. They could start off in awe, gradually learn the ropes of the battles, and form unexpected friendships or rivalries. For example, a character from a relatively unknown game enters and is initially intimidated by Mario and Link but then discovers they have unique skills that can hold their own. Another plot could revolve around a character's reaction to the constantly changing stages, like being really confused when suddenly transported to a new and wacky stage.