The Sand Snakes — the three bastard daughters of Oberyn Martell — sought vengeance against the Lannisters for the death of their father, killed while showboating in single combat against the Mountain (serves him right, gotta play to the whistle). And uh oh: Myrcella was in the hands of the Martells, betrothed to hunky Tristan and sent away by Tyrion to broker an alliance during the War of the Five Kings.

So Cersei, being a devoted mother/insane lady, sent brother/lover Jaime to Dorne on a secret mission to retrieve Myrcella … how, exactly? This was not plotted strongly. Anyway, Bronn accompanied Jaime — ostensibly for the money, but really so two of the show’s better characters could exchange repartée — and they were promptly captured in the Water Gardens. After meeting with Doran, Jaime left with Myrcella on a ship for King’s Landing. She was all, “I know you’re my father,” then the tender moment was interrupted by her death. Ellaria Sand (Mama Sand Snake) had kissed her goodbye with poison on her lips. Whomp-whomp.

House Martell

The Martells are the ruling family in Dorne, the warm southern peninsula of Westeros. They are subjects to the Iron Throne but were never conquered by the Targaryens, and that lends to their independent spirit. Unlike most other Westerosi, who are descended from the Andals and the First Men, the Martells are descendants of the Rhoynar, a people who didn’t practice primogeniture. Thus the head of Dorne is not the eldest male of the ruling family, but the eldest sibling. Progressive!

The current ruler of Dorne, though, IS a male: Prince Doran. Both of his siblings are dead because of the Lannisters: his sister, Elia, was raped and murdered by Tywin’s army during the sack of King’s Landing in Robert’s Rebellion, while brother Oberyn was killed in Tyrion’s trial by combat against Gregor “the Mountain” Clegane (also: Elia’s killer). Did I say “killed”? I meant “got his skull crushed like a grape.” It was gross.

So it at least KIND OF makes sense why Oberyn’s mourning concubine Ellaria Sand and their three daughters (the Sand Snakes) killed Myrcella with poison despite Doran’s plan for peace -- or if not peace, exactly, then at least a slower-developing plan for revenge.