Warning: this post contains spoilers for Orange Is the New Black season six.
Before they are in orange, blue, khaki, or even pink uniforms, the inmates of Litchfield are just regular people committing regular crimes. While the writers and producers of Orange Is the New Black show us some pretty dark offences — like Lorna's attempt to murder Christopher's girlfriend and the young boy who falls to his death while trying to leave Suzanne's apartment — season six introduces two new characters and one of the most gruesome crimes we've seen yet. Meet Barb and Carol Denning: they are the OGs of Litchfield, as we learn they've been in max for quite some time, and they're also the reason for the intensely divided C-Block and D-Block.
While Barb (Mackenzie Phillips) and Carol's (Henny Russell) crews are behind all the pranks and violence in the present-day season six, the flashbacks to their sociopathic teenage days immediately send chills down our spines. Frieda (Dale Soules) uses Suzanne (Uzo Aduba) to protect her in Florida throughout the whole season, but she finally explains to Crazy Eyes why she's been hiding from the Denning sisters in one of the final episodes. Although survivalist Frieda doesn't quite explain what she did decades ago to piss off the sisters, she does tell Suzanne about why they're in prison, referring to them as "the little Debbie murderers."
It's clear Barb and Carol hate each other now that they're in different prison families, but their hatred starts long before lock-up, back when they're just teenagers in the '80s. Their younger sister, Debbie, is a competitive gymnast, and their entire family is planning to relocate to Texas when she is accepted into a prestigious program there. The Denning family's lives revolve around Debbie's gymnastics career, and the older sisters not only resent her because of this, but want to kill her for making them move to Texas.
Older sister Barb is popular at school while Carol is extremely violent, drawing vivid images of them murdering their sister at her gymnastics meet. The contrasting sisters may hate each other, but they have one thing in common: they both hate Debbie more (the same way they mutually hate Frieda in the present day). The night before they are preparing to move, Barb and Carol are home alone with Debbie, and they tell her they'll take her to let her tadpoles free in a nearby lake. While Barb is standing with her sister by the frozen body of water, Carol chases after her with an ax, and Barb tells the adolescent girl to run and go hide in the car and lock the doors. Little does Debbie know that Barb dismantled the locks of all four doors and she's stuck in the car.
Barb and Carol push the car straight into the frozen lake, and we painfully hear Debbie screaming . . . until we don't anymore. The sisters talk out their monologue of what they're going to tell their parents, how Debbie locked herself in the car, and "you know how she always likes to play driver with Daddy." While it's not explicitly said in the show that their murder attempt is the reason they're in prison, we're assuming this brutally malicious act lands them behind bars.
When Carol bonds with Red back in the present timeline, she tells her new friend that she and Barb were initially sentenced to 25 years, but another 30 were when Frieda ratted them out and they were busted for drugs in the '80s. Well, after decades of murder attempts, season six ends with Barb and Carol killing each other with crafted prison weapons. We'll have to wait until season seven to find out if the C-Block and D-Block gangs will live on without them.