In November 2013, I was traveling in and out of southern Turkey. I'd come there for a number of reasons but most fundamentally to understand how the wars I'd fought in Iraq and Afghanistan were echoing out into the current revolution in Syria.

One evening, a friend of mine named Abed, who worked for a humanitarian aid organization and himself had been a democratic activist in the Syrian revolution, told me he'd met someone in a refugee camp who "he really thought I should meet." He explained that the man's name was Abu Hassar, that he'd fought for al-Qaeda in Iraq, and that he thought the two of us "would really get along."

A few days later, Abu Hassar and I met, two veterans of the Iraq war though we'd fought on opposite sides. Up to that point, the wars had been the defining event of my life. Fighting in them had been like a shadow dance, in which you never see your partner.

Ten years later, on that day in 2013, I wanted to meet my partner, this person who had so defined me. Meeting Abu Hassar was a gamble, because I was betting that my fascination with him would prove equal to his fascination with me.