After the fall of his father, Aerys, Viserys is the eldest surviving Targaryen. He is Daenerys Targaryen's brother, so he flees with her to Braavos, where he plots to find a way to restore their family to the throne. Part of his plan involves marrying his teenage sister to Khal Drogo, a Dothraki warlord, to get their support and military might.
Viserys's manipulations and arrogance eventually backfire, however. As Dany grows more sure of herself and becomes beloved by the Dothraki, they lose patience with Viserys. When he threatens Dany and her unborn child and demands his "crown," Khal Drogo has him killed by pouring molten gold on his head.