One idea could be a story where a humanoid Grimm has the ability to blend in with humans and is on a mission to infiltrate Beacon Academy. It could create chaos by spreading false information among the students. Another idea is a humanoid Grimm that has a strange bond with a Huntsman, and they have to figure out if they can trust each other or not. And perhaps a humanoid Grimm that is actually a failed experiment of some sort of dark magic, and it's trying to find its place in the world of Grimm and humans.
Well, you could write about a humanoid Grimm that was once a human who was transformed by some extreme Grimm power. This Grimm could be struggling with memories of its human life while still being driven by Grimm instincts. Or how about a fanfic where a group of hunters discovers a nest of humanoid Grimm that are evolving in a way no one expected, like developing their own language and culture. A third idea could be a humanoid Grimm that has a unique power, like the ability to control other Grimm, and it's using this power to wage a new kind of war against humanity.
A really cool concept for a RWBY humanoid Grimm fanfic could be a humanoid Grimm that has the appearance of a child. It uses this innocent look to get close to people and then attacks when they least expect it. This would play on the idea of how Grimm can be deceptive. Another interesting plot could be a humanoid Grimm that is part of a secret cult that worships the Grimm. The cult uses the humanoid Grimm to carry out their evil plans. And then there's the idea of a humanoid Grimm that is actually an ancient being, awakened from a long slumber, and it has powers and knowledge that no one in the RWBY world has ever seen before.
One idea could be a story where a powerful Demon Grimm is awakened by an ancient ritual gone wrong. The main characters in RWBY have to team up with unexpected allies to defeat it. They might discover new powers or abilities within themselves during the battle.
Writers often give them distinct physical features. For example, a humanoid Grimm might have multiple eyes or unusual skin textures. They also give them unique powers, like the ability to control shadows or manipulate ice in a way different from regular Grimm. Their backstories are important too. A humanoid Grimm could have been created from a rare experiment gone wrong.
One idea could be Ruby facing a new type of Grimm that has unique abilities, like the ability to manipulate time in a small area. This would put Ruby in a tough situation where she has to figure out how to combat it while being affected by the time distortion. Another plot could involve Ruby getting lost in a Grimm - infested area and having to rely on her wits and the little resources she has to survive and find her way back to her team.
One idea could be that the characters have to face a new type of Grimm that has emerged from the Pacific region. These Grimm could have unique abilities like being able to camouflage in the ocean or use water-based attacks. Another plot could involve the team having to form an alliance with a local group in the Pacific area who have their own ways of dealing with Grimm.
Some fanfic ideas could involve Grimm hybrids. For example, a Grimm that is part wolf and part snake, with the speed of a snake and the strength of a wolf. Another idea is to write about a world where the Grimm are not just mindless monsters, but have a complex society among themselves. How would the RWBY characters deal with that? Also, a fanfic centered around a character who has the ability to communicate with Grimm, but has to keep it a secret from everyone else.
One popular trope is the 'Redemption of the Humanoid Grimm'. In many fanfictions, a humanoid Grimm might start to question its nature and purpose. Another is the 'Forbidden Love' trope, like a human falling in love with a humanoid Grimm, which creates a lot of conflict and drama. Also, the 'Power Struggle' trope is common, where the humanoid Grimm is either fighting against other Grimm or trying to gain power among humans.
One idea could be a story where Velvet discovers a new type of Grimm with unique abilities. She then has to figure out how to combat it, using her skills and the help of her friends. Maybe she could study the Grimm's behavior and weaknesses in secret to surprise everyone when she reveals her knowledge.
Perhaps a fanfiction where a long - lost ancient magic resurfaces in a character, enabling them to control Grimm. The character then has to struggle with the moral implications of using this power, as controlling Grimm is generally seen as a very dark and dangerous ability in the RWBY universe. They might try to use it for good, like stopping Grimm attacks without harming the Grimm, but face opposition from others who don't believe it's possible to use such a power benevolently.
Well, one interesting idea could be exploring the relationship between Ruby and the Grimm in a unique way. Maybe she discovers a way to communicate with them, which changes the whole dynamic of the story.
A possible fanfiction could focus on a team-up between RWBY and Naruto characters against a common enemy that has the power of both Grimm and some dark ninja jutsu. For example, they might have to face an evil organization that is using Grimm to create chaos in the Naruto world while also using forbidden ninja arts. Or perhaps a fanfic could explore the concept of a RWBY character having a Sharingan - like ability that they gain in the Naruto world and how it changes their combat style and relationships with others.