Oberyn Martell
The Red Viper: Doran's hot-blooded younger brother ÔÇö poisoner, duelist, scholar and lover ÔÇö who has never forgiven the Lannisters for the murder of his sister Elia.
A soul of House Martell, born at Sunspear.
The fuller tale
Season Four
In Two Swords ÔÇö "The Lannisters aren't the only ones who pay their debts." Prince Oberyn Martell arrives for the royal wedding with a grudge older than the king. In Mockingbird ÔÇö "I will be your champion." The viper picks the fight he came for. Jaime can't fight, Bronn won't die for free ÔÇö and Oberyn Martell volunteers, for reasons carved in Elia's name.
In The Mountain and the Viper ÔÇö "Say her name!" He needed the words more than the win.
Where they stand. King's Landing.
Season Five
Dorne mourns Oberyn; Ellaria wants war on children; Doran wants proof and patience.
How it ends for them
On the screen. Killed in single combat (S4┬ÀE8)
The Red Viper danced circles around the Mountain in Tyrion's trial by combat, demanding a confession for his sister Elia. He got the confession ÔÇö with Gregor's thumbs in his eyes and his skull bursting in the Mountain's fists.
On the page. Killed in trial by combat (ASOS, ch. 71)
The Red Viper fought the Mountain for Tyrion's life and his sister's memory, poison on his spear and 'say her name' on his lips. He had his confession ÔÇö Gregor roared it while he crushed the prince's skull with his bare hands.
He dies in the duel he was winning, of the victory he actually wanted. Champion for Tyrion against Gregor Clegane, Oberyn fights the trial by combat entirely on his own terms ÔÇö a spear against a mountain, wine in one hand in the books' telling, poetry of footwork in the show's ÔÇö and puts the great knight down, poisoned steel through the armor's seams. Then, with the verdict his for the taking, he declines it: circling the fallen giant, demanding the confession, the name, the order-giver, refusing to end the collection before the debt is read out in full. The Mountain's hand finds his ankle; the rest is the story's most infamous minute ÔÇö Oberyn borne down, thumbs in his eyes, his skull burst in Gregor's fists even as the dying monster roars out the confession at last. Both tellings agree on every essential, including the bitter accounting: the Viper got his names said, Tyrion got a death sentence, and Gregor got Oberyn's manticore-venom parting gift, which the books make the seed of something worse than death. Dorne's answer to the news fills the rest of both sagas.
Their chapters, book by book
A Storm of Swords 2 chapters that name them
A Feast for Crows 1 chapter that name them
Where the page and the screen part
Book and show Oberyn are unusually aligned in character and diverge in aftermath: the books make him the trigger of the entire Dornish master-plot ÔÇö his death radicalizes Arianne's generation, forces Doran to reveal the Targaryen pact, and leaves eight Sand Snakes (not three) for the prince to disarm ÔÇö while the show routes his legacy into Ellaria's vengeance coup, a plot his book paramour explicitly argues against. Book texture the show trims: the Yronwood duel that named him, the maester's links, a stint founding a sellsword company, and his correspondence with the lamed Willas Tyrell ÔÇö the books' sly proof that the Viper's venom was always selective. The brothel diplomacy and the cell-side account of Elia are both tellings' shared jewels, near verbatim.
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.