Headbanging
A man, tired, carries his daughter onto the train as she rests her head on his shoulder and sucks her thumb. The train picks up speed and the man stands, resting from the waist on a suitably padded bench, with the girl half asleep and his back to the adjacent window. With each sideways rocking movement of the train, the girl’s head bounces with a varyingly gentility against the glass. She does not protest and he does not notice.