Tyene Sand
The sweetest-seeming of the Sand Snakes, daughter of Oberyn and Ellaria, who fights with daggers and poisons and a septa's pious smile.
The fuller tale
Tyene is the third of the Sand Snakes and the one built to be underestimated: golden-haired and blue-eyed in a family of dark Dornish looks — her mother was a septa, a fact she deploys with a straight face — with a novice's sweet manner, a needleworker's hands, and her father's doctorate in poisons. The books dress the joke to perfection: she looks like the Maiden and works like the Stranger, all soft blasphemies and gentle smiles, and even Doran's guards handle her gloves with tongs. Where Obara answers grief with a spear and Nym with a ledger, Tyene's petition to her uncle is the subtlest: no armies — just let her whisper in the right ears, and war will come to Dorne asking to be let in.
Doran, who knows exactly what each niece is, posts her accordingly: in the books Tyene is bound for King's Landing in a novice's habit, sent to burrow into the Faith just as the Sparrows rise — a poisoner embedded in the realm's new conscience, one of the published saga's most quietly alarming loose threads. The show kept the sweetness-and-venom exterior, gave her twin daggers, a flirtation with Bronn conducted at antidote's edge, and a place in the family coup; the habit, the Faith and the long game stayed on the page.
The page and the screen
The tellings share her surface — the septa's daughter, the poison, the smile — and split her purpose entirely. Book Tyene's infiltration of the Faith militant is unbegun on screen; show Tyene instead stabs Areo Hotah in the back during the coup and spends her last arc as a prisoner of the plot's consequences. The 'bad pussy' fight at the Water Gardens and the poisoned-blade flirtation with Bronn — cut, cure and all — are pure show invention, as is everything that follows from Euron's ambush. Her book self has never been captured, never touched her cousin's guard, and is last seen being fitted for a habit with murder in its hems.
Where they stand, season by season
Their fate — if death has found them, it is written here. Open at your peril.
The show: Lost in King's Landing (S7·E3)
Captured with her mother and marched through King's Landing, she was given the same poisoned kiss Ellaria gave Myrcella — while Cersei made the mother watch, chained just out of reach, for as long as the light lasted.
The show gives her the story's most engineered death: a mirror held up to her mother's crime. Captured with Ellaria when Euron's fleet takes the Dornish party at sea, Tyene is marched through King's Landing and delivered to Cersei, whose daughter Myrcella died of Ellaria's poisoned farewell kiss. In the black cells, Cersei administers the sentence she has clearly rehearsed: the same poison, the Long Farewell, pressed to Tyene's lips with a kiss — and the antidote drunk in front of them — while mother and daughter are chained to opposite walls, close enough to see and never to touch. Ellaria's punishment is to watch it, and then to keep watching for as long as her own life is maintained; Tyene's death arrives on the poison's slow schedule, off camera, with the certainty of arithmetic. In the published books Tyene Sand is alive, en route to the Faith, her kisses so far entirely her own business.