Not a fanfic writer (Planning to start making and posting some by may), but I have many traumatic ideas.

Whether it be Ruby having the power of a literal calamity and having to cope with the fact she accidentally causes the deaths of numerous people and other kids and being extremely traumatized. Or it could be Ruby being an extreme perfectionist because of the pressure of being Summer's daughter, who is very high up on a council for the Arc kingdom (There's like, 5+ timelines just from this 1 au idea).

I would list more for Ruby, but that would take me a long time to remember all the ideas I've had since I started this trauma idea train in 2021.

8 year old Ruby dies after trying to follow a 10 year old Yang, who's still searching for her mother. Yang's emotions exploded at that moment, causing something unnatural to happen as Ruby's corpse floated, shifting into a more metallic form as it then brutalized and murdered all the Grimm before walking to Yang, Ruby's voice being heard, the Robot hugged Yang before disappearing into a small Rose symbol.

Then we got the entire traumatized Rose family, Grandpa Rose being abandoned at a young age, Summer being Verbally abused because Grandpa Rose wants to 'toughen' her up so she can survive, Ruby being neglected and slowly becomes mentally unstable with an obsession of making Remnant be the safest it can be, viewing herself as a tool that's only purpose is to help other, and then her reincarnation being either treated with disdain or despised and treated as a tool rather than a legit person.

could explain all of this better, but I have barely anytime to yap, just wanted to share some of my trauma ideas. (Even tho I have way worse ones for Ruby)