Olenna Tyrell
The Queen of Thorns: Mace's mother, matriarch of Highgarden, and the sharpest tongue in the Reach — a tiny old woman who runs her house and fears no one at court.
A soul of House Tyrell, born at The Arbor.
The fuller tale
Season Three
Arrives in King's Landing for the business of marrying her granddaughter well, and wastes no time letting Tywin Lannister know she is neither intimidated by him nor impressed by the crown's finances, needling him about Lannister debts to Highgarden with open relish. Spots an opportunity to marry Loras to Sansa Stark and secure a claim on Winterfell through her, and loses the idea within days when Tywin outmaneuvers her by marrying Sansa to Tyrion instead — a rare defeat, and one she doesn't pretend to enjoy.
Season Four
Margaery marries Joffrey at last, and the wedding does not survive the feast — Joffrey chokes and dies at the high table, and among the small, easily missed details of that afternoon is Olenna leaning in to admire the hairnet Sansa Stark is wearing, and a stone that isn't there anymore by the time anyone thinks to look for it. Whatever really happened, Margaery is free of one husband and being fitted for a kinder one within days, and Olenna does not so much as blink through any of it.
Season Five
Watches the High Sparrow's Faith Militant return to King's Landing with a foreboding nobody else at court seems to share, and is proven right within the season — Loras arrested on old charges revived new, Margaery arrested alongside him for lying under oath to protect her brother, and Tommen too besotted and too outmaneuvered to do more than plead. Olenna argues the High Sparrow to a standstill and gets nothing for it, and leaves the capital in disgust rather than watch a king she considers useless fail to save her family.
Season Six
Returns to King's Landing for Margaery's walk of penance, expecting to see her granddaughter through the ordeal — and instead watches the Sept of Baelor go up in wildfire with Margaery, Loras, and half the city's high lords inside, Cersei's doing, though Cersei is never made to answer for it that day. What remains of House Tyrell she puts behind Daenerys Targaryen's war, not out of any love for dragons but because Cersei has made an enemy of the one Tyrell who was never going to let a debt like this one go unpaid.
Season Seven
Holds Highgarden in the name of Daenerys's alliance while the queen's attention is elsewhere, and it costs her the city — Jaime Lannister marches on it while the main Tyrell strength is off supplying Dany's army, and takes it in a rout. Cornered, Olenna refuses to run and refuses to beg, and when Jaime offers her a clean death by poison instead of a public one, she takes the cup without flinching and spends her last minutes telling him, precisely and with some satisfaction, exactly whose hand put the poison in Joffrey's cup all those years ago — and making sure Cersei is never to know it was her.
How it ends for them
On the screen. Took poison on her own terms (S7·E3)
When Highgarden fell to Jaime Lannister she bargained only for the manner of it: poison in wine, painless, on her own terms. She drank it down and then told Jaime the truth about Joffrey. 'Tell Cersei. I want her to know it was me.'
The show gives her the exit she would have chosen from a catalogue. When Highgarden's storied walls fall in an afternoon to Jaime Lannister's army, Olenna waits in her tower for the victor with the composure of a woman receiving an overdue tradesman. Jaime, in a mercy Cersei would not have countenanced, offers poison in wine over the axe or the rope; Olenna drinks it down without ceremony — and then, payment rendered, delivers the most lethal exit line in the series: the truth that it was she who murdered Joffrey, with the request that Jaime tell Cersei it was her. She dies off-screen, on her own terms, having turned even her execution into a weapon. In the published books she is alive at Highgarden, the amethyst hairnet's secret still holding.
Their chapters, book by book
Where the page and the screen part
Book Olenna is a smaller part played to identical effect: the lemon-cake interrogation of Sansa, the running demolition of her son, and the necklace — the books' version is a hairnet of black amethysts — are all page material, and the purple wedding's choreography matches nearly beat for beat, down to the reader catching her at the fatal adjustment only in hindsight. Everything after is the show's invention: in the published books she departs for Highgarden after the wedding and remains there, alive, her house ascendant rather than embattled — no Sparrow duels, no alliance with Daenerys, no siege. The show's expansion made her a fan-favorite institution; the books' version remains a scalpel used precisely twice.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.