About twice a week, between fourth and fifth period, at their high school, in a hallway with eleven hundred people in it, my son walks next to Maya Lin from one end of the building to the other.

He does not push her.

He has never pushed her and she has told him, in detail, what will happen if he ever does.

He does not carry anything for her.

He does not open doors, because the doors have buttons.

He walks beside her, slowly, at the speed she is going, and as far as I can tell from the one time I have asked they talk almost entirely about a video game and about a girl in their chemistry class.

It costs nothing.