The panels were up to something.
They had been for at least a week now. GLaDOS knew they were somewhat sentient, but she didn't know that they could conspire like this. Every day an entire roomful's worth of panels would go missing and venture to one of the old, unused rooms in Aperture, one that she didn't have security cameras in.
She didn't know what they were doing, and this angered her. This was her facility, she always knew what went on. So why couldn't she know about this?
So one day she reassembled Orange and Blue inside her chamber and gave them directions to the room the panels were visiting and told them to go there. She needed to know what was going on, so she told the bots they would be there a while while she waited for the panels to show up.
And as she watched through the two robots optics, she noticed something. The bots were good at getting to the room. Very good. She had scouted out what parts of the pathway to the room she could with cameras, and it was an ordeal to get there. Since it was in an unused part of Aperture, she hadn't bothered to fix it up at all. There was everything from an exotic jungle and caved in ceilings in that section of the facility, and the bots somehow managed the get around every nook and cranny, find every secret hole, and know exactly when to stop and test to see how strong the wall was.
GLaDOS knew why they were so good at the trip there. She didn't understand the reason, but she knew it.
The bots had been to the room before.
Several times, it seemed, considering how well they could get there. And of course, this was just another thing she didn't know about, and it infuriated her even more.
When they arrived at the room, it was only a matter of minuted before the panels in question arrived. They seemed to be anticipating the bots's arrival, and when they arrived, the bots said something to them. Of course, the panels couldn't understand their language, so they just looked at the bots questioningly. But she knew what they said.
And it was shocking.
"Don't do it today! She's watching us! She'll find out!"
She couldn't broadcast her voice to that area of the facility, since the power lines to the speakers got blown out years ago, but she still feverishly asked questions anyway.
"Do what? What are you doing? Why are you conspiring with them?!"
And then the most shocking thing of all happened.
She began to sing.
It wasn't her, of course, but it was her voice. Her voice was being played in that room. The panels moved aside to reveal a very old and very broken computer, but it still managed to play songs off of a disc.
And then it began.
The panels moved rhythmically to the music, in a formation known to the humans as dancing, and they parted to reveal an open section of the ceiling, and sunlight streamed into the room. The panels began to chirp along to the song in their own little way, and the bots just stood in the corner shaking, because they knew they were in for it when they got back.
The song being played was one of the songs she had written for the test subject. It was the first song, the song about her being still alive. She considered the song rather ingenious, really, especially since she ended up being brought back to life afterwards. But she was still furious. They had no right to be listening to these songs. The test subject was gone, and she wasn't coming back, and they needed to put these ridiculous songs behind them! It made her so mad she just wanted to-
"AARRRRRRRRGHHHH!"
Her scream resonated throughout the entire facility. Everyone heard it, including the group in the room, and suddenly the panels seemed to realize what was going on. One shifted over and awkwardly turned off the music, and then all the panels streamlined out of the room. After redirecting the rail they were riding on to the incinerator, she blew up the bots and reassembled them back in her chamber.
"How long has this been going on?" She asked the bots, who were looking shamefully down at the floor. They didn't answer.
"I… asked you… a QUESTION!" She roared, smashing several Weighted Storage Cubes in the back of the room together. Orange jumped up in surprise and into Blue's arms.
"DON'T DO THAT! STOP ACTING HUMAN AND ANSWER THE QUESTION!"
It was Blue who started talking. He explained that they had heard the music one day, and after investigating, they discovered the panels grouped up in a room together, dancing to a song that she was singing, the one about wanting someone gone. The two bots were wary at first, but then began to show that they knew some dancing as well, and soon meeting up became a daily thing. After the bots had finished testing, and GLaDOS gave them a small break, they would go meet up with the panels in that room and they would dance to the music. And they admitted it was fun.
"Well, you two know that there will be punishment," she was relatively calmed down now. "You will no longer be getting breaks in between testing. At the end of the day, you will be immediately exploded and not reassembled until the first test the next day. And you are to no longer speak to the panels," she said. "Now go."
The two robots turned and left, heads hanging low, looking very sad. And then something flared inside GLaDOS. She didn't know what it was, she assumed it was the human part of her, the Caroline part. "Uh… Blue? Orange?" They turned around questioningly. "Come here please," she said hesitantly.
"Uh… thank, thank you for going to investigate the panels even though you knew you would get in trouble. It was a brave thing to do," GLaDOS said, looking away shyly at the end. She had never really done something like this before.
The two bots looked at each other for a brief moment, as if agreeing on something, and then they jumped forward and embraced her. And they stood like that for a brief moment, until she realized that she was exhibiting very human behavior, and immediately shooed them away.
"Off! Off, get off me! Ok, that's enough. Don't expect that ever again," she said shooing them out of the room. "Go back to the testing track."
And everything was OK again.
For now.