Mostly they dance. They never make eye contact, never open their eyes fully. Half-lidded, they zone out on the music that pulses incessantly through their pens, lost in the feel of their bodies, in movement.
The glass is one-way. Looking up, they see only themselves. It is safe to be on outside; you may stare as long as you want without worrying that they are staring back at you.
They are kept scrupulously clean. At night, after the last commuter has shoved into the last car, water jets unhood within the walls and they are hosed down. While they sleep, exhausted, lulled by the gentle narcotic in their food, attendants enter and groom them: trim hair and nails, polish skin until it glows, remove blemishes with tiny lasers.
Sometimes the meniscus breaks. One sits, defiantly still, a carton of food in its long hands, eyes sullen through the mirror. An eddy forms before it; the throng pauses, surprised, intrigued. For a few weeks they are fed in front of the mirrors, until the commuters grow accustomed, lose interest.