At the foot of a Union Square subway platform staircase, an artist focused on his delicate work, maneuvering a fold of black origami paper along half-open scissor blades.

“Scissor doesn’t move, only paper moves,” he said to the rider posing for him. “Nice young man,” he bantered. “How old are you? Like your hair.”

The paper’s border flutters to the dirty, gum-tacked floor. He peeled open the fold to reveal an intricate, slightly caricatured portrait of the rider’s face, down to the hairs and wrinkles. He taped it to a white-tiled wall beside him, joining it with others, oblivious to the gusts from the passing trains that threatened to blow his frail creations onto the tracks.

On a foam board below were dozens more subway characters: man with dreadlocks, woman with hoop earrings, bald man with spectacles. He offered to repeat the feat without looking at the rider’s face. “In America, just me,” he said of his skill. “In China, just me. This unique.”