SOME 300 YEARS ago, Laos was partitioned into the competing Kingdoms of Luang Prabang, Vientiane and Champasak. They were all ruled by descendants of the same king, and through eras of war, annexation, encroachment and colonization by the Siamese, Vietnamese, Chinese and French, their lines endured such that in the two stormy decades after the country’s 1953 independence, the heir to one house, Prince Souvanna Phouma, held the title Prime Minister frequently, trading for a time with the heir to another, his cousin Prince Boun Oum. The chairman of the Pathet Lao, Prince Souphanouvong, was Phouma’s half-brother, and, in a way, thank goodness for that because when the communists took over and he became president, he ensured safe passage out of the country for many of his royal relatives… And…