Rhaegar Targaryen

Silver-haired, melancholy, and beloved by half the realm, Rhaegar was everything Robert was not: refined, brooding, a harpist rather than a brawler. He crowned Lyanna Stark queen of love and beauty at Harrenhal in front of his own wife, and whatever happened afterwards — abduction, elopement, prophecy, or some tangle of all three — it ended with a rebellion.

They met at last in the waters of the Trident, and Robert's warhammer ended him and the dynasty together, scattering rubies into the current. It was the defining moment of Robert's life, and he was still hating the man fifteen years later with an energy that suggested he had never really won. The Trident settled a war. It settled nothing else.