The hybrids' origins are pretty much made of this. Kidnapped from their real families, whom have no idea what happened to them and are left to presume their children dead, they were immersed in the Grimm-spawning Pools of Annihilation (which are literally destruction embodied) in order to turn them into Grimm hybrids similar to Salem; with their capacity for positive emotions locked away, with an appetite for violence, bloodshed and other carnal urges instilled in them, and with their memories of their former lives and loved ones suppressed. Some of the kidnapped children dipped in the pools just die, and those that do survive and become hybrids are then condemned to a life of violence, bloodshed and savagery in the Academy of Evil; routinely thrown to the wolves and expected to violently kill each-other off under a "survival of the fittest" mentality.
Being reared as a hybrid is bad enough, but on top of that, Ruby spent most of her life before Jaune showed up being ostracized and pariahed by her peers on account of her lingering capacity for positive emotions, which she and the other hybrids have been taught to revile.
Salem reveals that she's been keeping Summer Rose alive in a dungeon... and routinely forcing Ruby, who doesn't remember her human family after her Grimmification and considers Salem to be her mother, to go confront the former. Summer tries to spark Ruby's memories of her, bringing up the cookies she used to make Ruby among other things, to no avail.
Later, when Jaune gets a one-to-one conversation with Summer, it's clear that ten years of being forced to endure this psychological torture have taken their toll on her. She tells Jaune in no uncertain terms that she's given up on ever being freed or rescued, she's sure that he'll die trying to save her and her daughters before he ever succeeds at the objective, and she's sure that Taiyang has killed himself out of grief. The only smidgeon of hope she can bring herself to muster is that Jaune will make Ruby and Yang a little happier during his time with them.
As Ruby bursting into a crying fit without even knowing why she's doing it shows, her memories from when she was human aren't completely gone. They still exist somewhere in her subconscious, and that unconscious part of her which remembers hurts.
Once Jaune has exposed his secret (the fact that he's human) to a hybrid in the academy, he's truly on the cusp of despair and is almost certain that he isn't going to live another day.
When Blake activates her Aura in a class demonstration, the exposure to her repressed human emotions causes her to immediately break down in a sobbing and screaming fit, crying out about her father and revealing that she didn't want to kill Adam (whom her Grimmified self tortured to death before taking his severed head as a reminder).
The flashback where Raven, amid the fallout of Summer, Ruby and Yang's disappearances, returns to Taiyang's house on Patch for the first time since she abandoned him and Yang. Raven has been shaken to her core by discovering the fates which Salem has inflicted on Ruby and Yang, keeping this information to herself and letting her former-teammates believe that they died out of mercy toward them. When Raven sees Tai, he's a broken shell trying to drink his sorrows away — which Raven mentally notes is a very far cry from the confident, kind, optimistic and upbeat ladies' man he once was — and he eventually makes it clear to Raven that he's seriously contemplating suicide.
Bear in mind, canon makes it clear that Tai didn't handle Summer's death well at all at first, to the point where Yang had to pick up the slack taking care of things. This Taiyang hadn't even finished processing the apparent death of his second wife when both their daughters disappeared into Grimm-infested woods one day and were never found. He has truly lost everything at this point.
In the wake of the seeming deaths of Summer, Ruby and Yang; Taiyang and a shaken Raven ended up getting back together, and they've even had a new child together. Except Ruby, Yang and Summer are still alive, the former two as hybrids and the latter as a prisoner of Salem: and it turns out Ruby and Yang aren't nearly as too far gone as Raven believed they were when she lied to Tai and Qrow about their fates, while Qrow intends to rescue Summer and he eventually brings Raven around to helping him. However this ends, someone in the family is gonna be hurt.
Raven saw with her own eyes what Salem had turned Ruby and Yang into, then, believing that the persons the hybrid girls once were are gone and there's no saving them, she abandoned the girls to their fates, and she lied to Qrow and Taiyang to let them believe Ruby and Yang were dead in a genuine empathetic effort to spare her former-teammates the horrifying truth. Except Raven was wrong about there being nothing left of the real Ruby and Yang's souls inside the monsters, as Jaune has proven over the course of the fic. It's easy to imagine that one of the reasons Raven is as stubborn as she is in her assertions that the human Ruby and Yang are dead and that Qrow is a delusional Zombie Advocate for believing otherwise, is because the alternative if Qrow's right means that she abandoned hers and her teammates' daughters to a living hell under Salem's machinations for ten years, for nothing.
Unlike Ruby or Weiss, Yang does remember her human past, but she's incredibly bitter and disillusioned about it even after she unlocks her Aura. She blames her father, her uncle Qrow and both her mothers for failing to save her and Ruby from their fates and feels that they abandoned them, leaving her with nothing except Ruby, violence, and an immortal monster for her third mother who wouldn't mourn any of her children's passings by "survival of the fittest" in the slightest. She's completely cold and belligerent towards Qrow after they reunite, and she wholly expects him to try and kill her. Unlike Ruby and Weiss, Yang initially rejects her reawakened humanity because she hates the feelings of regret over everything she's lost.
During Team AWRY's first sparring class with Qrow, Qrow demands that "Yara" come forth and kill a Boarbatusk as a class demonstration, passingly using his elder niece's "Firecracker" pet-name which makes it clear that he knows who "Yara" really is. Yang proceeds to brutalize and toy with the Boarbatusk in an outright sadistic manner, until Qrow suddenly loses his composure and shouts at her to finish the creature off already: Qrow is clearly shocked and rattled at getting his first glimpse of what his little "Firecracker" has become in ten years since she went missing.
The entire chapter where Weiss goes crazy due to unlocking her Aura and attacks Winter. The ensuing fight sees both sisters maimed by the other, and they come away from it shaken and permanently scarred.
When Weiss finds out that Jaune is human, she at first tries to rationalize it by saying that she achieved the apex of her human-infiltrating mission by seducing and making a mate out of a real-life human... which devolves into her tearfully saying she doesn't want to kill Jaune.
Winter, when telling Weiss about their family, shows regret for not being there for Whitley to provide a counter to their Abusive Dad's influence.
Yang's reaction to seeing Raven. After attacking Raven in a rage, Yang eventually breaks down and tearfully asks her why she didn't love her. The monster is fully peeled back to reveal the broken, traumatized girl underneath.
