ATLAS and P-body trod nervously down one of Aperture Laboratories' many service corridors, ever directed by GLaDOS, who was tracking the turret by fleeting glimpses on security cameras and, more often, camera feeds suddenly being cut as the cameras were destroyed. Out of camera range, GLaDOS could only wait for the robots to report in.
Unbeknownst to them, the turret silently stalked them, crawling along the wall, a good twenty feet over their heads. Just like his creator, Luke knew nothing about the Co-operative Testing Initiative. He did, however, have an extensive understanding of personality cores and turrets, which seemed to be the inspiration behind the two robots' design. Using the keen, scientific mind Rattmann had gifted him with, Luke calculated a detailed estimation of their anatomy before leaping from the wall, and onto the catwalk the two robots were navigating.
Spinning around in reaction to the sound Luke had made, P-Body quickly rose her portal gun and began firing frantically. After several balls of orange light phased harmlessly through Luke, she seemed to remember that her gun wasn't a weapon, and instead lifted it above her head and hurled it at the turret, which he effortlessly evaded. In retaliation, Luke deployed the rifles on one side of his body and fired a single bullet, which sailed neatly through the top of P-body's head, which, after a couple of seconds, prompted her to fall flat on her face.
Dropping to his knees, ATLAS frantically shook his fallen partner and wailed desperately. Having temporarily forgotten his mission (to say nothing of the fact that both he and P-body were incapable of dying), ATLAS looked up in surprise as Luke whistled invitingly. A millisecond after whistling, when Luke perceived ATLAS' head to be at precisely the right angle, a second bullet sent the more masculine robot slumping to the catwalk.
"Hello? Hello? Wow Blue, if I were calling for Orange to report in, they'd do it right away, I guess all the things Orange has been saying about you aren't as mean as I thought."
GLaDOS waited, hoping to have provoked the robot into sending a reply, but none came. She switched frequencies.
"So Orange, Blue was just telling me what a failure you are. How about you get back to me and we'll figure out how we can take them down a notch?"
Moments later, GLaDOS had resigned herself to the fact that ATLAS and P-body had been destroyed. She wasn't surprised. The pair of imbeciles weren't built for combat, she had only sent them because they were convenient. No, if she was to take down this killing machine, she'd need to accelerate her plans, so that she'd be ready to deploy some killing machines of her own.
Back in the maintenance tunnel, ATLAS and P-body slowly began to stir. Under Luke's observation, their eyes slowly re-illuminated and they began to climb to their feet. Once their reboot was finished, the pair of robots grasped their heads and chattered at each other illegibly. Unfamiliar with the new sensation, it was a while before either of them realized what had happened. With surgical precision, Luke had destroyed the wireless relay which GLaDOS used to communicate with the two robots when they weren't on testing courses, and destroy them when they finished.
Upon the realisation, ATLAS lifted P-body of her feet with a crushing hug and cheered excitedly. Dropping her clumsily, he turned and did the same to Luke, prompting the renegade turret to speak for the first time.
"Put me down…"
ATLAS shuddered. Although Luke's voice was highly reminiscent of his siblings', in its robotic monotone (not to mention he had coined a more than familiar phrase), his voice was deep and commanding, with none of his siblings' desperate whine. ATLAS crouched down and very carefully set the turret on the catwalk and backed away.
"We have work to do…"
With that, Luke turned around and scuttled back towards the lab, with ATLAS and P-Body chasing loyally behind.