Test Chamber Seventeen was simple. GLaDOS highly doubted that this particular test subject would have any difficulties with it, since she had managed to complete the far more difficult Test Chamber Sixteen so quickly and easily.
All the subject had to do in this chamber was carry the Weighted Companion Cube, specially designed to coerce subjects into forming an attachment to it, through the chamber and use it to help her solve a few simple puzzles. Then at the end, the subject would have to abandon her beloved cube in an Aperture Science Weighted Companion Cube Receptacle, which was the real test. Most of the time, this caused test subjects to suffer a small bout of depression, sometimes complete with hysterical sobbing. GLaDOS couldn't wait to find out how this test subject would handle it.
"The Vital Apparatus Vent will deliver a Weighted Companion Cube in three…two…one…"
As it fell out, the subject took a step backwards, narrowing her eyes at the cube with suspicion. When it didn't threaten to harm her, she stepped back towards it, examining it, and then smiled, rubbing a hand along one of the hearts on the cube's faces. GLaDOS hypothesized with some satisfaction that this test subject would more than likely have a difficult time letting her Companion Cube go.
And sure enough, the subject was reluctant even to stand on the cube, and even more so to use it as a shield against the energy pellets. After she was clear of the danger, she examined the cube carefully for any injuries, and, much to GLaDOS's annoyance, used the sleeve of her Aperture Science Official Test Subject Jacket to wipe off some of the soot left by the pellets.
After she had accomplished that, the subject completed the portion of the chamber that required her to use the energy pellets. It astounded GLaDOS how fast this particular test subject was in comparison to all the others before her.
But then the subject did something the AI never would have predicted: After first looking around to ensure there was no danger, she lay down on the ground. She then hugged the Companion Cube to her chest, snuggling against it, and closed her eyes.
After checking through her databases, GLaDOS determined that the human was attempting to sleep.
"The Enrichment Center wishes to inform you that this is not a good time to sleep," she informed the subject through an intercom. "You only have two more test chambers to complete, after this one. Once you are done, you may sleep all you like. After you consume your victory cake, of course."
Instead of responding to the AI's perfect logic by standing up and continuing with the chamber, the subject opened her eyes just long enough to glare at a camera and clutched the Companion Cube even tighter. Miffed, GLaDOS tried again.
"This is not an acceptable course of action. If you persist with it, you will not receive any cake."
The subject didn't even bother with a glare this time. Her breathing had slowed to a steady, even rhythm, which GLaDOS knew meant she was asleep.
"[Subject Name Here], wake up," she ordered. "Wake up immediately. I'm not kidding now. Wake up, or there will be no cake at all!"
But despite GLaDOS's best efforts, the test subject refused to wake up, and finally, the AI gave in with a loud sigh.
"Oh, fine. Fine. But as soon as you awaken, you will complete the test. And since you seem to be so attached to that Aperture Science Weighted Companion Cube…" She let her voice trail off menacingly, even though she knew that the test subject couldn't hear her.
While the subject slept, GLaDOS changed the last part of the test chamber to make it as difficult and as painful as possible. And when the subject woke up at last, the AI said nothing, choosing instead to just watch as she continued through the test chamber.
When the subject reached the final room, she looked around in confusion, unsure of what to do. GLaDOS took the opportunity to begin spouting the prewritten messages she'd pulled together while the subject was napping.
"You did it! The Weighted Companion Cube certainly brought you good luck." At that, the subject let out a small smile, giving one of the cube's hearts an affectionate pat. GLaDOS had to fight to keep the smirk out of her voice as she continued. "However, it cannot accompany you for the rest of the test and, unfortunately, must be euthanized."
GLaDOS took great pleasure in watching how quickly the test subject's face went from content to horrified.
The next half-hour was spent watching the test subject agonize over the decision. She alternated between stroking the cube and pacing, her face grim. But GLaDOS had to give her credit for one thing: she never cried.
And at long last, after pressing her lips to one of the cube's hearts and giving it a small kiss, the test subject stood with a determined expression. She completed the euthanization process within seconds, lingering only to watch the cube fall down the incinerator shaft with a sad expression on her face.
"You euthanized your Companion Cube more quickly than any subject on record," GLaDOS said, not bothering to add that she was the only subject on record to euthanize her Companion Cube. "Congratulations."