One interesting 'eren isn't human fanfiction' could be where Eren is some kind of ancient spirit reborn. In this story, he has powers that are beyond human comprehension and he uses them to protect his friends in a very different way than in the original plot. His non - human nature makes his actions more unpredictable and the story full of twists.
If Eren isn't human in fanfiction, it can change the power dynamics. For instance, if he has non - human strength, he might be able to defeat enemies more easily, altering the battle scenes and the overall threat level in the story. This could also affect how other characters view him, from being a normal comrade to a being that they both fear and rely on.
A major theme is often power. Since he's not human, he might have special powers. The fanfictions explore how he uses or struggles with these powers. Also, the theme of secrecy comes up a lot. Stiles may need to keep his non - human side a secret from some people, which creates a lot of tension.
One interesting idea could be exploring how Lucy, not being human, views the human world. Maybe she has unique perspectives on human emotions like love and friendship that are different from our own.
One possible plotline could be Hermione being a magical creature in disguise. Maybe she's a veela, which would add an interesting dynamic to her relationships. Her beauty would be even more alluring and it could cause some jealousy among her peers.
He could be a demon. In some fanfictions, Naruto might be reimagined as a powerful demon with unique abilities that are different from his normal human ninja skills.
If Naruto is a non - human, say a god - like being. The plot could develop around other characters' reactions to his true nature. Some might fear him, while others might try to use his power for their own gain.
Another plot could involve Stiles trying to hide his non - human nature from his friends, especially Scott. This would create a lot of tension and secrecy in the story. He'd have to constantly come up with excuses for his strange behavior or powers.
Draco Malfoy could be another character. His interactions with Hermione would be full of tension. If Hermione is non - human, he might be even more jealous or spiteful, or perhaps he could develop a begrudging respect for her unique abilities that set her apart from ordinary witches.
One idea could be that Bella is a vampire hunter who was turned into a vampire against her will. Now she has to navigate the vampire world while still holding onto her human values. Another could be that she's an alien disguised as a human named Bella, and she's on a mission to study Earth's culture. Maybe she falls in love with a human and has to decide whether to reveal her true identity.