She knew she had to go. Away from this hell, away from all the pain it had caused. She decided a direction, and prepared to walk away. But then it struck her; her companion cube! How would she take it with her? Should she just leave it? Back in the test chambers, she discovered that the cubes are, simply said, too heavy to lift. She'd estimated it was heavier that herself (despite what she would make you believe!), so she couldn't just pick it up. She couldn't just leave it here, either. She eventually settled on a simple compromise; based on what she found out in Manufacturing, the turrets' parts were simply locked into place, making them surprisingly easy the destroy. She can remember the satisfaction of destroying one of those. If the cubes were made the same way, then maybe…
She approached her cube, and gently started pulling on one of the round pads, with the heart on it. She pulled increasingly harder, until it snapped off with a satisfying clunk. She held it in her hand. Turns out those cubes are cheaper than they look, after all. She admired the round object for a bit, then stuffed it in her back pocket. The only thing that didn't try to murder me, she mused, and went on her way.
(-)-(-)
After about two hours of walking, she noticed just how quickly she got tired. With the adrenal vapour in her system, moving around without stopping was a piece of cake, no pun intended. She was somehow still in the wheat field. It seemed as though it never ended. She wondered how exactly Aperture's former employees managed to get to the place; maybe there was a sort of metro system hooked up to the underground labs. Knowing Aperture Science as well as she did, that didn't seem like such an unlikely thing. Couldn't she have just sent her on her way on that thing then? Well, if it even existed that is. Maybe they'd used a portal to get there. She imagined all the employees coming in one by one through a portal, as she walked up a hill.
Her train of thought quickly came to a halt, as she saw a small dirt road coming out of the ground, and stretching into the forest in front of her. She walked down the hill, approaching the hole in which the road disappeared. It had a rolling shutter, like those on garages, and upon further inspection, she saw the Aperture logo on it. That's one mystery solved. She thought. She then began focusing on the forest in front of her.
It was close to nightfall, and it was about time she'd drink something. After a few minutes of walking, she encountered a small stream of water. She approached it, cupped her hands, and collected some water. It was refreshing, after walking for two hours straight, and judging by the quality of the road, she was probably a long way away from civilisation.
After getting her priorities in order, she decided to make a fire. She hadn't encountered any form of life apart from plants since she was free, so she'd have to eat fruit from nearby plant life. She gathered up some twigs, leaves, and other dry material, and decided to settle just beside the forest. She'd have to find food soon, but that would have to wait until tomorrow.
She set up a fire by rubbing some sticks together, and since it was quickly becoming dark, she lied down against the hill, preparing to sleep. At that point, she felt something in her back pocket. She took it out to see her ripped off part of her beloved Companion Cube. She held it tightly against her chest, as she dazed off into sleep.