For a RWBY Beowolf OC fanfiction, you could focus on a Beowolf OC that has a connection to a particular location. Say it haunts an abandoned mine in Vale. It could have made the mine its lair and is territorial about it. The OC could have a backstory related to how the mine was once a place of great activity and the negative energy from its abandonment attracted it. The RWBY team stumbles upon this mine during a mission and has to face this territorial Beowolf OC. You could also play with the idea of the Beowolf OC evolving or changing its form as the story progresses, maybe due to absorbing some sort of powerful energy source in the mine.
One idea could be a Beowolf that has some unique mutation (xm could imply a special mutation perhaps) and it forms an unexpected alliance with a RWBY character. For example, it could be that the Beowolf has a special ability to sense danger in a different way and it warns Ruby of an upcoming large Grimm attack. This could lead to Ruby trying to understand if the Beowolf can be tamed or not.
One way to develop the personality of a RWBY Beowolf OC is to think about how it interacts with other Grimm. Does it lead the pack? If so, it might be more dominant and assertive. It could growl and snap at other Beowolfs to keep them in line. Also, consider how it reacts to humans and Huntsmen. Is it more curious than afraid? Maybe it has seen some Huntsmen in action before and is intrigued by their power, so it hesitates before attacking. This kind of personality trait would add depth to your OC in the fanfiction.
Well, for a RWBY new weapon in fanfiction, think about a weapon that has the ability to manipulate the elements. For instance, a staff that can create fire, ice, or lightning at its ends. Or perhaps a pair of gloves that can harden into metal fists for punching and also generate shockwaves. A whip - like weapon that can split into multiple smaller whips for wider area attacks is also a cool concept. These weapons would add new and exciting elements to the RWBY fanfiction battles.
An OC in RWBY fanfiction could be a character who is a master of stealth. They could use their skills to gather intelligence for the teams at Beacon Academy. Their backstory could involve growing up in a family of thieves, but they decided to use their abilities for good. They might have a Semblance that allows them to become invisible for short periods of time, but it has a drawback like draining their Aura quickly. This OC could interact with characters like Blake, who also has some stealth - like abilities, and they could learn from each other.
For RWBY OC fanfiction, you could make an OC who has the power to manipulate time on a small scale. This would be a really cool ability in battles, being able to slow down opponents or speed up oneself. Another idea is to have an OC that is a faunus with a very rare animal trait, like a phoenix - like faunus. Their story could revolve around hiding their true nature because of discrimination. And an OC that is a transfer student from a far - off land with a completely different fighting style compared to the students at Beacon Academy would also make for an exciting story.
Another idea is that the Ladybug characters end up in the RWBY world. They would be shocked by the Grimm and the more dangerous environment. Ladybug and Cat Noir could team up with RWBY teams to fight off the Grimm. Along the way, there could be exchanges of combat techniques. Ladybug could teach RWBY characters some of her acrobatic moves, while the RWBY characters could show them how to handle different types of weapons.
Well, you could have an OC mercenary who has a special bond with a Grimm. Instead of fighting Grimm all the time, this OC has found a way to communicate and even control a certain type of Grimm. Maybe it's a small, less - dangerous Grimm at first, but as the story progresses, they learn to handle more powerful ones. Or an OC who is a technologically - advanced mercenary, using high - tech gadgets and weapons that no one in Remnant has seen before. Also, an OC with a tragic past as a mercenary, like they were once part of a group that was betrayed, and now they're on a quest for revenge while still taking on mercenary jobs.
You could make your OC have a special power related to speed. They could be faster than any of the RWBY characters, which would make for some exciting fight scenes. Their motivation could be to avenge their family who were killed by Grimm. In the fanfiction, they start out as a loner but gradually form bonds with the main RWBY characters as they realize they have a common enemy.
One idea could be an OC who is a healer in the hospital and has to deal with the unique injuries of RWBY characters. For example, they might struggle to heal a Grimm - inflicted wound that has some sort of dark magic attached to it. Another idea is an OC that discovers a new type of Dust - based medicine in the hospital, which could revolutionize the way injuries are treated in the RWBY world. And also, an OC who is a patient in the hospital and has amnesia, and throughout the fanfiction, they slowly regain their memories and realize they have a special connection to the RWBY universe.
One idea could be to cross your original character (OC) with the world of RWBY and have them be a transfer student at Beacon Academy. They could bring unique skills or powers from their own world, like a magic system that RWBY doesn't have. Another idea is to have the OC be from a different time period and get thrown into the RWBY universe, causing all sorts of chaos and new storylines. For example, an OC from a steampunk world with advanced machinery could introduce new tech to the RWBY characters.