John is perching on one of the metal stretchers that rests beneath a host of tools, all ready for the call of the computer nearby. It's perfectly harmless, almost inert aside from the hum of the system. Being here, out of the way of the flood of those escaping the tanks, allows him to both collect himself and watch over everyone else. He hears her call, and the tremor in it as well.

It takes a moment, but he's got his knuckles against his lips and is giving one, sharp note of a whistle in her direction. He can't tell if he's catching her eye or not, but he gestures with a hand for her to come over.