Warning: This post contains mild spoilers for Season 6 of Orange is the New Black.

I was 10 episodes into Orange is the New Black Season 6 when I realized I was truly invested.

I wasn't ride or die for the show's central couple, Piper and Alex, or for Nicky's quirky quips as she tries to save Red. I care deeply about Taystee, but I was tired of how much of her story was inexplicably spent on Joe Caputo and his corporate love triangle (blegh).

No, what got me in was Carol and Barbara Denning, a.k.a. the "Little Debbie murderers" held in maximum security prison probably for the rest of their lives (Henny Russell and Mackenzie Phillips, respectively). The warring siblings (who killed their kid sister when they were teens, played by Ashley Jordyn and Lauren Kelston) run Litchfield Max and their feud is the most compelling thing in Season 6.

Image: jojo whilden/netflix

We meet and learn about the sisters bit by bit; from Freida's flashback, from Daddy's employment, from Nicky's cell block and whispers throughout the prison that eventually lead Red to Carol's inner circle. The Denning sisters entered Litchfield as allies, but petty sisterly squabbles escalated within the prison walls to a full-on gang war between C and D block.

We only get two flashbacks with the sisters – one about the crime that got them imprisoned, and one in which Freida betrays them to go to minimum security. Both episodes are a welcome shift from the usual flashback style and structure. They're set roughly in the late 1980s, a world that feels genuinely removed from others' backstories and recent crimes. The Denning sisters, young and old, have a rough edge in how they conduct themselves, a magnetic appeal in their scornful demeanor.

We've seen ruthless women on Orange before. Carol and Barb's enmity doesn't bubble up like Red and Vee in Season 2, but it echoes notes of that epic rivalry. In their younger iterations, they are as much petulant teens as they are cold-blooded murderers. I want three hours of Heathers but Dennings – not even a killing spree, but a dark comedy Orange special full of gallows humor and cold laughter.

Image: jojo whilden/netflix

Orange is the New Black has always been a show by and for women, and women of diverse ethnicities, sexualities, and ages. The older women are tough and weathered (not physically, but from like, prison). I could watch and rewatch Henny Russell sipping alcohol from a shampoo bottle while turning prison showers into her personal day spa.

No spoilers, but the war between the Dennings takes over the later part of Season 6, with a truly dark comedic payoff (whether or not it's satisfying is another question). In the flashback about that "glass of ice" story, we learn that it happened to neither of them, that they absorbed the anecdote from a coworker (a black girl, and that's no accident). The scene reveals their immeasurable selfishness – which we sort of sensed when they killed a child in order to avoid switching schools – as does the present scene in which they stage a massive gang fight in order to exact personal revenge.

The Dennings represent a type of criminal we haven't yet seen on Orange, but which we have seen in any depiction of men in prison: One who lacks a conscience. By virtue of the show's writing and all-female inmate cast, every criminal we've met so far on Orange had a notable streak of compassion or humanity (even Vee's manipulation of Taystee came from a soft spot...somewhere). These ones aren't afraid to draw blood, to shove someone under a bus or into a frozen lake. There's bleak comedy in their story, but bleak is what it ultimately amounts to – bleak and utterly fascinating.

We probably won't see much more of the Dennings, given that Orange's seventh season may be its last and we've got to catch up with some of the other inmates and deal with the finale fallout for Flores, Taystee, and Piper. But it sure was something to get to know them, if only for a little while.

Orange is the New Black Season 6 is currently streaming on Netflix.