Afterwards, we paused to eat, Joel producing fruit and cheese and water from a small refrigerator that I had missed on the other side of his computer. As we ate, I drew out of Joel how he had for a long time, harbored fantasies of his mother. After we ate, the teenager took me to his computer and as I sat on his lap, he showed me what he had been working on when I had arrived.

"It's a 3-D cartoon," he explained, "Of me and Mom and my fantasies." He called up image after image of a computer generated woman who looked amazingly like his mother. Grace, doing all...