content: 
  == Storylines ==
  In ''A Storm of Swords'', Oberyn leads a Dornish envoy to King's Landing to claim the seat on the small council on Prince Doran Martell's behalf and obtain justice for his sister Elia Martell's murderer, as was agreed with the acting Hand of the King, Tyrion Lannister.  When Tyrion is accused of murdering King Joffrey Baratheon, Oberyn volunteers to champion for Tyrion in the trial by combat, so he can fight and seek revenge from the rival champion, Ser Gregor Clegane, who is Elia's murderer.  Though Oberyn manages to gain the upper hand in the duel and impale Clegane to the ground with his spear, Clegane manages to surprise him by foot sweeping him to the ground and bear-hugging him, then gouging his eyes, and finally killing him by repeatedly smashing his face with a mailed fist.  However, it is later revealed that Oberyn has coated his spear in manticore venom to ensure that Clegane will die a slow and agonizing death.
  In ''A Feast for Crows'', Doran Martell reveals to his daughter Arianne that Oberyn has actually been acting as Doran's enforcer to carry out his secret plan for House Lannister's downfall.  Three of Oberyn's bastard daughters, known as the Sand Snakes, are assigned missions to infiltrate the Iron Throne as sleeper agents.