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Warning: Spoilers ahead through Season 7, Episode 3 of Game of Thrones.

“Your daughter will die here in this cell,” the one mother, Cersei, informs Ellaria, the other. “And you will be here watching when she does. You will be here for the rest of your days .... You will live to watch your daughter rot, to watch that beautiful face collapse to bone and dust. All the while contemplating the choices you’ve made.”

Tyene, murdered—with agonizing slowness—before her mother’s eyes: It’s yet another circular story in an episode (and, indeed, a show) that is full of them. Here is Cersei, getting her revenge for the death of her daughter by forcing the woman who murdered Myrcella to endure roughly the same fate Cersei had: the loss of a child. The grief that comes with knowing that a beloved daughter will never grow up to have a full life. Cersei, she notes to her prisoner, could punish Ellaria in any number of physically excruciating ways—and yet she chooses, cunningly and tellingly, the way that forces Ellaria to know her own pain: Ellaria, it seems, will watch Tyene die. The mother will be made, Cersei says, to keep company with the daughter’s decomposing corpse. Ellaria’s punishment will come in the living, rather than the dying.

It’s a revenge that, even for Game of Thrones, is particularly horrifying, and particularly cruel. But the murders in question, the death of the one daughter avenged by the apparent death of the other, have something in common: The horror starts, in both cases, with a poison kiss.

Poison, in Game of Thrones as in the world beyond it, is traditionally a weapon of last resort. It is calculating. It is deliberate. It reveals itself not on the battlefield, but in the background. And it is used, generally, not for crimes of passion, but rather for killings that are planned, patiently, over time. Poison is a tool of asymmetric warfare—one that is used, often, when the other side is unaware that there is a war being fought in the first place. A little bit science, a little bit magic, it is deployed, in general, by those who have no other choice.

Which is to say that, in pop cultural stereotype if not in practice, poison is often considered a weapon of women. As that ancient adage goes, “Trust none of the dishes at dinner: Those pies are steaming-black with the poison Mummy put there.” As that Dixie Chicks song demurs, “Those black-eyed peas, they tasted alright to me, Earl.” In England, the House of Lords tried to pass a law forbidding women to buy arsenic. The attempt was made in the 19th century—and yet the thinking that led to it persists today. It’s not that boy, after all—miss her, kiss her, love her—who is poison.

Game of Thrones has, over its six-plus seasons, both embraced and complicated that stereotype. On the one hand, poison, true to its cultural resonances, has been a favorite weapon of the show’s women: characters who are often relatively powerless, characters who are often relatively desperate. Ellaria used poison—delivered via, yes, that deadly kiss—to murder Myrcella. Arya used poison to kill the Freys and their confederates: a mass murder executed with ease, with the help of poisoned wine. Lysa Arryn used a similar tactic (wine, laced with toxin) to kill her husband Jon. Olenna, the Tyrell matriarch confirmed on Sunday, used poison to kill Joffrey at his wedding. And the Sand Snakes, the daughters of Oberyn, were distinguished in Game of Thrones not merely according to their signature weapons, Teenage Mutant Ninja Turtle-style, but also through their affinity for weaponized venom. Snakes, and all that.

“I heard it said that poison is a woman’s weapon,” Ned Stark tells Maester Pycelle, at the outset of Game of Thrones. “Yes,” Pycelle replies. “Women, cravens ... and eunuchs.”

As the show has advanced, though, it has complicated that blandly gendered idea, considering poison not just in relation to gender politics, but also in relation to power politics more broadly. The Sand Snakes picked up their toxin-appreciation, after all, from their swaggering father. “Any man who calls a poison ‘a woman’s weapon’ is a traitor to his fellow men,” Oberyn declares. “A dagger, arrow, axe. These are the arms of passion. But poison is cold, calculating. Poison is the thought that wakes you in the morning, and lulls you to sleep at night. You watch your victim die a thousand times before you ever offer him that fateful taste. Is a man’s hate so inferior to a woman’s that we are to be denied such a weapon?”

Poison, in this sense, is an equal-opportunity weapon—the tool not of the woman, but of the vigilante. It is used by those who have given up on (or who, indeed, never believed in) a communal notion of justice. In a show that is deeply interested in the morality of killing—a show in whose moral universe the how of a death matters as much as the fact of it—poison is the refuge of the rogue. It stands in contrast to the state-sanctioned killings that are often enacted reluctantly, but for a broader purpose (as when Ned Stark executes Will, the deserter of the Night’s Watch, or when Daenerys executes Mossador, her erstwhile advisor, for his own failure to respect the queen’s version of justice). Maester Pycelle may have been right—poison may be, often, used by women—but more to the point it is used by those who have decided to operate beyond the sanction of their societies. To kill someone with poison is to reject the rule of law.

It’s an attitude that gets a new twist in “The Queen’s Justice,” an episode that is bookended with poisonings. In many ways, the apparent death of Olenna Tyrell at the hands of Jaime Lannister was the opposite of the seeming death of Tyene Sand at the hands of Cersei: Olenna will (ostensibly) die alone, while Tyene will (ostensibly) die in the company of her mother. Olenna voluntarily—almost eagerly—gulps the poisoned wine Jaime had given to her, after he assures her that her death under its influence will be quick and relatively painless. Olenna’s demise is, technically, suicide; Tyene’s is, technically, murder.

And yet both poisonings suggest a kind of karmic circularity: Tyene is killed with the same toxin Ellaria used to kill Myrcella. Olenna is killed in roughly the same way that, it turns out, she killed Joffrey. Olenna, alone in her tower bedroom, might have been vanquished. She may have been out of choices. And yet her death comes, remarkably, on her own terms. She drinks the poison. And Jaime allows her that small bit of human dignity afforded to those in Game of Thrones who are killed not out of vengeance, but out of justice: Olenna gets to utter last words.

And those words are, fittingly, poisonous. “I’d hate to die like your son,” Olenna says, coolly, “clawing at my neck, foam and bile spilling from my mouth, eyes blood-red, skin purple. Must have been horrible for you, as King’s guard, as a father. It was horrible for me, a shocking thing.” She pauses, to let her words’ full effect sink in. “Not at all what I intended.”

You could read Olenna’s speech as an act of atonement: an admission of guilt uttered while she is still able to make the admission. But Olenna, of course, does not seem sorry. She seems gleeful. She seems like someone who is using her final moments to enable one last act of vengeance against the woman who has won the battle, but not yet the war. “Tell Cersei—I want her to know it was me,” the Tyrell matriarch tells Jaime. She seems to understand that vengeance is its own kind of poison. And she seems to understand that words, like toxins, can be their own kind of weapons.

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