The killer came by night – a masked man on a motorbike who struck without warning and then sped away. It's become a familiar pattern in some corners of the new Syria in recent months, as the country's fragile unity is eroded by revenge attacks and sectarian killings. The main targets are Alawites, the sect of the ousted Syrian President, Bashar al-Assad. But this time, on 1 October, the victims were Christians – Wissam and Shafiq Mansour, cousins who were both 39, and were as close as brothers.