Years ago, Rukia's mentor and object of worship, Kaien, was demonically possessed trying to avenge his wife's death, forcing Rukia to kill him. Believing she deserves to die for this, she accepts her execution sentence over Ichigo without a fight, until Gin offers to save her life just as she's walking to the gallows. When he reveals he's joking, she finally breaks, collapsing on the bridge and screaming in despair.
When Aizen has Orihime kidnapped, poor Orihime is subjected to psychological conditioning, mental torture, implied rape threats, physical abuse and being forced to watch Ichigo have a hole ripped through his chest, Uryuu having his arm diced off and the enemy being completely untouched. Her mental breakdown resurrects Ichigo as a single-minded monster so focused on his goal of saving her that he not only kills her captor but also nearly kills Uryuu, too. What was done to her at Hueco Mundo was awful because she is such a sweet and caring girl who weeps for even her enemies. Moral Event Horizon much?
Hinamori dearly loved Aizen, who took pride in grooming her for decades to be unable to survive without him. He even manipulates her into thinking her adoptive brother betrayed her, before leaving her deeply traumatised, broken-hearted and almost dead. Just as she's finally recovering, Aizen manipulates Hitsugaya into stabbing her almost to death.
Aizen takes advantage of Hitsugaya's youth and lack of experience to manipulate his adoptive sister to the point of insanity. Eventually, Aizen fools Hitsugaya into thinking he's successfully killed Aizen, only to reveal he's actually stabbed Hinamori. Cue Roaring Rampage of Revenge.
Rangiku and Gin were childhood friends but she was betrayed by him when he joined Aizen's side. After she was victimised by Aizen's Hougyoku experiments, Gin vowed to avenge her. He plotted revenge for a century, but ultimately fails, and Rangiku is reduced to a sobbing wreck as he dies.
By the time Tsukishima gets through with everyone, Ichigo finds himself alone in the world as friends and family are all completely brainwashed against him. His one single ally turns out to be the real villain and promptly steals the power Ichigo's worked so hard to regain, leaving Ichigo a spent, sobbing wreck.
