A plot could involve Ruby getting a special power-up related to Unlimited Blade Works. For example, she could gain the ability to project multiple versions of her scythe, like how some characters in Unlimited Blade Works project their weapons. This new power would change the way she fights and she would have to train to master it while also dealing with the threats in her RWBY world that are now more dangerous with this new ability.
Perhaps in the fanfiction, there is a crossover event where the Unlimited Blade Works reality starts to merge with the RWBY world. Ruby is at the center of this, as she is the main character. She has to figure out how to stop the merge from causing chaos. Along the way, she discovers secrets about her own powers and the origins of the two worlds, and forms new relationships with characters from both RWBY and Unlimited Blade Works.
In such a fanfiction, Shirou Emiya could be an ally. He has experience in Unlimited Blade Works and his skills in swordsmanship could complement Ruby's scythe - fighting style. They could learn from each other and fight side by side against common enemies.
A fanfic could focus on Ruby teaching parkour to some of the younger students at Beacon Academy. It could start with her demonstrating some basic moves, like wall -running and precise jumps. Then, as the story progresses, the students face a challenge on campus that requires them to use the parkour skills Ruby taught them. Ruby could also share some of her own experiences in combat where parkour was crucial.
Maybe a plot where Ruby discovers a hidden part of her family's past that links her to the Scarlet Spider in some way. This could lead to her having to learn new abilities or face a moral dilemma as she gets involved with the Scarlet Spider's more gritty and morally ambiguous world compared to the more straightforward good - vs - evil of RWBY.
Well, in some fanfictions, a male Ruby might be from a different background than the original Ruby. This could lead to an interesting dynamic with Weiss. For example, he could be from a more noble family, which causes some initial friction with Weiss, who is also from a noble background. As they work through their differences, a White Rose relationship begins to develop. It could involve them facing off against a new type of Grimm that only male Ruby's special skills can help defeat, bringing them closer together.
One possible plot could be that Ruby Rose somehow gets transported to Equestria. She might initially be confused by the magical and colorful world. The ponies could be both curious and a bit scared of her scythe and combat skills. Ruby could then team up with the Mane 6 to face a common threat that requires both her combat abilities and the ponies' magic. For example, a new kind of dark magic that is corrupting the land and only Ruby's speed and fighting skills along with the ponies' unique magics can stop it.
A third plot idea is that they participate in a tournament together. They have to compete against other teams from different academies. During the tournament, they face some tough opponents who target their weaknesses. Ruby and Blake have to train hard together to overcome these challenges. In the process, they learn new techniques from each other and their relationship evolves from just being teammates to being really close friends who trust each other completely.
One possible plot could be that Ruby discovers a lemon - scented oil that has a strange effect on Crescent Rose. When she applies it to her weapon, Crescent Rose starts to emit a lemon - colored glow. This new feature attracts a special type of Grimm that is only drawn to this lemon - like energy. Ruby has to figure out how to use this new situation to defeat these Grimm and also understand the origin of the oil.
Well, one plot could be that Ruby's mother faked her death and is actually alive in hiding. Ruby discovers some clues that lead her to believe this and goes on a journey to find her mother. Along the way, she has to face various challenges and enemies who are also after her mother for their own reasons.
One type of fanfiction could be set in an alternate universe where Ruby uses Crescent Rose in a completely different way. Maybe she uses it for non - combat purposes like using the scythe part to cut through thick foliage in a forest she's exploring. Or it could be a time - travel fanfic where she has to use Crescent Rose to defend herself against enemies from a different era.
One idea could be a story where Ruby and Coco team up for a special mission. Maybe they have to infiltrate an enemy base, and Ruby's speed and Crescent Rose combined with Coco's fashion - inspired weapons and strategic mind make them an unbeatable duo.