A unique plot for a RWBY Demonic Grimm fanfic could involve a prophecy. The prophecy states that a hero will rise to defeat the ultimate Demonic Grimm, but in order to do so, they must first gather several powerful relics scattered across Remnant. Along the way, they face many Demonic Grimm that are guarding these relics. These Demonic Grimm are different from the regular ones as they have special powers related to the relics they are guarding. For example, one Demonic Grimm guarding a fire - related relic can breathe out intense flames that are not like the normal fire attacks of regular Grimm. The hero and their friends must overcome these challenges and finally face the ultimate Demonic Grimm to fulfill the prophecy.
One plot idea could be a group of hunters discovers a new type of Demonic Grimm that can possess other Grimm, creating an army. They have to find the source of this new threat and stop it before it overcomes all of Remnant. Another could be a young huntress in training who has a special ability to sense Demonic Grimm and she teams up with some unlikely allies to face a powerful Demonic Grimm lord that has been hidden for centuries. A third idea is that the Demonic Grimm start to corrupt the minds of some of the hunters, turning them against their own kind, and the remaining hunters have to fight both the Demonic Grimm and their former comrades.
First, think about the origin of the Demonic Grimm. If it was created from some dark, ancient magic, it might have an otherworldly and terrifying look. For example, it could have a smoky, ethereal body with a skull - like face that constantly changes expressions to show its malevolence. Its attacks should be unique and deadly. Maybe it can drain the life force of its enemies just by touching them. And don't forget about its behavior. A Demonic Grimm that stalks its victims silently, always lurking in the shadows before pouncing, would be very scary.
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 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.
Often, there are plots where Pyrrha has to protect her friends from a horde of Grimm. This emphasizes her loyalty and self - sacrifice. Some fanfics also explore the idea of Pyrrha having a special connection to the Grimm, like being able to sense them in a unique way, which then leads to various adventures and challenges as she tries to understand this connection and use it to her advantage in the fight against the Grimm.
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.
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, perhaps there could be a fanfic where Slender Man is actually an ancient evil that was sealed away in the RWBY world long ago. And due to some recent events, like the opening of a certain relic or a powerful magic spell gone wrong, he is released. The RWBY characters then have to figure out his weaknesses by researching old legends. Or it could be that Slender Man has a connection to the White Fang. He uses their anger and desperation to his advantage, secretly manipulating them to do his bidding while the RWBY gang tries to stop this new threat.
Well, a possible plot in 'rwby controls grimm fanfiction' is that the whole team RWBY starts to experiment with Ruby's new - found ability to control Grimm. They could face moral dilemmas, like whether it's right to use the Grimm as weapons. Maybe they try to use controlled Grimm to gather intelligence about Salem's plans. Or, they could accidentally create a new type of Grimm - hybrid when Ruby's control goes a bit wrong during an experiment.