Yandere Yang au/Yangdere au
Yang had to deal with a dead mother, absent uncle and Other mother, emotionally unavailable father, a toddler She must raise since she was 5-ish, the destruction of her school, the death of her friends, being forcefully amputated by her friend’s ex, being left by said friend, being thrown into another world, and Watching Her Sister DIE IN FRONT OF HER! And a few more things I’m missing.
So it wouldn’t be too surprising for her separation anxiety to devolve into obsession of those she cares about.
For example, after V9 Yang would likely become more protective of Ruby and Blake to the point of keeping them from doing their duties as huntswoman under the pretense of needing to save their strength for the fight against Salem. Perhaps, after the defeat of Salem, Yang does what ever she can to keep her team together by any means necessary. Blake is easy, as the two of them are already dating, and Ruby, being her sister, quickly follows suit, especially after the loss of Penny for a second time. However, Weiss is a different matter entirely having no issues leaving for some time to help Whitley get the SDC back up and running the way their grandfather had envisioned (that traitor). So, Yang decides to make sure that Weiss can’t (be stolen from) leave them again.
Even if it means breaking a leg or both.