I first met Qassem four years ago, at the height of the European refugee crisis. The BBC had sent me to capture the stories of Mideast migrants, thousands of whom would daily wash ashore on the Greek isles. He was around 15, malnourished and clearly traumatized. As we sat together in a cabin at a migrant camp on the island of Lesbos, his hunched body rocked backward and forward. His marginal life amounted to a speck of dust amid the geopolitical earthquakes that were remaking the region at the time. Yet the story he told opened a window onto the...