Stevie Mackenzie’s brother broke up the family. He emailed her a few days after Thanksgiving to announce it. He would no longer be coming home for Christmas. John Armstrong—the family called him Army—had decided to spend the holidays in San Francisco with friends. His friends didn’t try to shove him in a box and tape it shut. His friends understood his situation.

A year went by, and Army stayed away again. Stevie and her parents fought to keep him. Eva, the older sister, was strangely neutral. Fewer pieces in the pie? Maybe. Perhaps she had a problem with intimacy. Whatever the reason, Eva was willing to let him go.  She and Army had much in common: strong chins, advanced degrees, jobs in technology. They even attended the same gadget conventions in Las Vegas. At one of these, they lunched.