Another plot could be set in a post - apocalyptic scenario within Remnant. Ruby and Coco find themselves as part of a small group of survivors. They have to deal with limited resources, internal group conflicts, and of course, the ever - present threat of Grimm. Their leadership skills and ability to inspire others in the group would be put to the test as they try to find a new place to call home.
One idea could be that Ruby and Coco team up for a special mission in a dangerous, uncharted part of Remnant. They face new Grimm and have to rely on each other's unique skills to survive. Coco's fashion - sense - related weaponry could combine with Ruby's speed and scythe skills in interesting combat sequences.
Maybe they participate in a tournament together. During the tournament, they have to face some tough opponents who are not only strong physically but also have some tricky strategies. Ruby's inexperience in some social aspects of these events could be balanced by Coco's more confident and worldly attitude. And they learn from each other along the way, strengthening their friendship and combat synergy.
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.
One idea could be Ruby discovering she has some cheetah - like abilities. Maybe she's faster than ever and has to learn how to control this new power. It could add an interesting dynamic to her combat style and how she interacts with her team.
A third plot idea could be Ruby having to face an ancient vampire threat that is related to her new condition. Maybe she discovers that she was turned into a vampire as part of a bigger plan by an evil vampire lord, and she has to stop this villain while also coming to terms with her own vampirism. This could involve her learning about vampire lore and using it to her advantage.
One plot idea could be Ruby discovers she has werewolf abilities during a mission in a forest. She has to learn to control it while still fighting the Grimm. Another could be that there's a curse in Beacon Academy that turns Ruby into a werewolf, and her friends have to find a way to break the curse without hurting her.
One idea could be Ruby having to relearn her combat skills while being deaged. It would add an element of struggle and growth as she tries to regain her former abilities. Maybe she forms new friendships with characters she already knew in a different way because of her new, younger perspective.
A really interesting plot would be if Ruby's Reaper form was somehow connected to an ancient prophecy in the RWBY world. Maybe it was foretold that a Reaper - like figure would either save or doom Remnant. This would put Ruby in a very difficult position, with different factions having different views on her and her new form. Also, a plot where Ruby has to team up with some unlikely allies while in her Reaper form to take on a common threat could be cool. These allies could be former villains who see the greater danger that requires Ruby's power.
One plot idea could be Ruby discovering she has werewolf abilities during a mission. She has to learn to control it while still fighting Grimm. Another could be that in a werewolf form, Ruby has enhanced senses that help her track down a powerful and elusive enemy. Or perhaps she forms a pack with some of her friends who also get werewolf-like powers and they have to protect Vale from a new werewolf - Grimm hybrid threat.
One idea could be Ruby adjusting to her new cyborg body and the enhanced abilities it gives her, like super - strength or advanced weaponry integration. Another could be her facing discrimination from some in the RWBY world who fear or mistrust cyborgs.
Adventure is also a popular theme. Writers often send them on quests or missions together. For example, they might be exploring an unknown part of their world, facing dangerous Grimm. This allows for exciting action scenes and the opportunity for the two characters to bond further during the adventure.
One great Ruby and Coco fanfiction is 'The Unlikely Duo'. It has an interesting plot where Ruby and Coco team up for a mission that was initially thought to be a simple one but turns out to be full of twists and turns. The author does a great job of portraying their different personalities and how they complement each other during the adventure.