Wheatley was overwhelmed.

For starters, he was rubbish at math, in fact he was pretty sure one of the reasons he was chosen to be the Intelligence Dampening Sphere was his complete inability to understand anything numerical. And yet he was the one doing the bills.

Wheatley sighed as he checked his answer for the 78 & 1/2th time in five minutes. He was no expert, but he was pretty sure they couldn't afford to send Sophie to high school, let alone med school like she always wanted. And if their financial trouble wasn't enough, the Cube was acting up again.

Chell had kept the metal box to remind herself of how lucky she was, but for reasons they didn't particularly want to understand, the Companion Cube always started playing music in the week leading up to the anniversary of Chell's escape. Maybe it was GLaDOS' sick idea of a joke. But the point was, it was dangerous. If Sophie found it, and it somehow led her back to Aperture, he could never forgive himself. (There was also the whole thing with Sophie learning about his past and hating him for the rest of forever, but that wasn't important.)

Wheatley wished he could help, he really did. But short of selling the Companion Cube or the Long Fall Boots (bad idea), there was nothing he could do. He just hoped Sophie didn't resent him for this.

Unfortunately, Wheatley was so absorbed in his thoughts, he forgot to hide the Cube in the basement.

Later

The moon was almost full, but no one noticed thanks to a massive rainstorm (Earth's climate was still recovering from the Combine's terraforming, so random storms like this happened occasionally. But hey, at least it wasn't acid rain). In fact, this rainstorm was so massive, Sophie's bedroom ceiling had developed a leak. Hence why she was currently in a sleeping bag in her parent's room, having just been startled awake by a clap of thunder.

Sophie was just about to go back to sleep when she heard a strange noise coming from a few feet to her right. Wait, that wasn't noise, that was music. Why was there music coming from her mother's closet?

Carefully, Sophie crept out of her sleeping bag, walked to the closet, and slowly opened the door.

After shifting a few boxes, she found the source of the sound, a metal cube about 1 1/2 feet in diameter.

"What is this thing, a safe? What have my parents got to hide?" Sophie knew she shouldn't be snooping in her parent's closet, but as much as she was her mother's child, she sometimes displayed traits from Wheatley, and one of those traits was stupid curiosity.

As Sophie attempted to pry the top off of the strange box, she heard a faint *click* and the music abruptly stopped. Then, hearing her father muttering something about piano lessons, she quickly put the cube back in it's hiding place, closed the closet door, and darted back into bed.

The Companion Cube no longer made any audible sound, but had Wheatley still been a robot, he would have heard the shrill, dog-whistle like sound of a homing beacon.