I am standing in Berlin Central Station, all my belongings tucked in a locker, a piece of paper with a phone number in my pocket. I had come to see the Berlin Wall before it was torn down completely. Somewhere along the train ride, I met Tracy, another young American woman, and we tacitly agreed to stay together in Berlin. Hesitant to impose on a total stranger, the phone number in my pocket was a last resort, but our search for lodgings had...