Maybe in the fanfic, Ruby gets drunk and starts reminiscing about her childhood and how she got into the whole Huntsman business. She could share some really cute and endearing stories that her friends haven't heard before, making for a heart - warming scene. And then she might pass out in an odd position, much to the amusement of the others.
Another concept is that Ruby, while drunk, mistakes a Grimm for a friendly creature. She tries to approach it and befriend it, which of course scares her teammates. They have to quickly come to her rescue without hurting her feelings too much, because she's in this drunken state of confusion and naivete.
Well, one interesting idea could be Ruby's transformation into a Saiyan-like form. It might bring new powers and abilities that she can use in the RWBY universe. Maybe she gains super strength and speed, like Saiyans in the Dragon Ball series.
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.
Perhaps the story could explore how Ruby's pregnancy affects her relationships with her team members. Some might be overly protective, while others could struggle to accept the change in her situation. It could also be interesting to see how her pregnancy impacts her relationship with her weapon and combat abilities.
One idea could be Ruby meeting a wolf Faunus who is initially mistrusted by the group but later proves to be an ally. Maybe the wolf Faunus has a special ability related to tracking that helps Ruby and her team in a mission. Another plot could involve a wolf Faunus who is being hunted by some anti - Faunus group and Ruby decides to protect them, which leads to a series of battles and the exploration of the discrimination against Faunus in the RWBY universe.
One idea could be Ruby discovers a new form of nanotech in a hidden part of Remnant. This nanotech could enhance her Crescent Rose, giving it new abilities like shape - shifting or self - repair.
One idea could be a story where Ruby and Scarlet team up to face a new, powerful Grimm that has unique abilities. Maybe it can manipulate time, adding an interesting twist to their battles.
In some 'rwby dark ruby fanfiction', there might be the idea of Ruby being corrupted by an ancient evil force. This could lead to her having to fight against her own nature as she is slowly turned into something she hates. It can also show how her friends try to save her from this dark path, which makes for a really engaging story.
One plot idea could be that Ruby discovers a hidden stash of nanobots that were created by an ancient civilization in Remnant. These nanobots start to malfunction and cause chaos in Vale. Ruby has to use her skills and Crescent Rose to contain and fix the nanobots. Another idea is that a villain uses nanobots to control the minds of some of Ruby's friends, and she has to find a way to break the control and defeat the villain. A third plot could involve Ruby teaming up with a scientist to study the nanobots and use their unique properties to upgrade her weapon or gain new powers.
Another plot could involve Ruby and Weiss, in their Futa forms, having to protect a group of innocent Fanus from a powerful enemy. This would test their combat skills as well as their friendship and teamwork. They could also learn more about the discrimination that Fanus face in the world and strive to make a change.
One idea could be that Ruby, with her speed and enthusiasm, helps Pyrrha break out of her more reserved shell. For example, Ruby could drag Pyrrha into some crazy training sessions that are more about having fun than strict discipline. This would allow Pyrrha to relax a bit and not be so focused on always being perfect.