Disclaimer: I don't own Portal or Left 4 Dead which is what this is crossed over with. Its mostly just a headcanon of mine that those two games could be taking place in the same place. You never know, the 'green flu' infection Could have been started by something out of Aperture. According to Cave Johnson they did make mantis men after all

"Aw c'mon please Dad?" the redheaded teen asked her father. It was her 18th birthday and her father had said she could pick something she wanted to do, he just hadn't expected her to want to explore outside the facility. "It'll be so quick! GLaDOS will be busy with other test subjects that she'll never even notice!"

Harris hesitated. He knew this really wasn't a good idea, but he did also know his daughter. If he said no now there was a Very high chance she would just try to sneak out on her own, getting herself in serious trouble if not killed. Harris sighed, pinching the bridge of his nose. "Fine. But we'll go only when I say and you'll stay in my sight at all times."

"I'm 18, not 8, Dad."

"It's either that or not at all."

Carly sighed, but nodded in reluctant agreement. "Fine..."

…

A few hours into the day when GLaDOS was indeed focusing on some of the other test subjects, Harris and Carly snuck their way up and out of the facility, making sure to avoid any and all cameras.

Once outside in the wheat field Carly started to explore, while having to be reminded several times to not go too far ahead.

As they looked around the field, something in the distance caught Carly's attention. She went off quickly to go see what it was with her father close behind. Once they got close enough to see, they were horrified to see it was a hooded figure clawing at another person.

"Carly", Harris whispered, "back away slowly. No sudden movements." Harris kept his voice down while he and Carly backed up away from the bloody sight. But, as they crept away, the hooded person turned and looked right at them, blood dripping from its face. "Run, Run!" Harris called louder, grabbing his daughter's arm and after they turned to run, he shoved her ahead of him further from the bloody person.

Carly and Harris ran quickly through the wheat trying to get back to the shack with the elevator. The hooded person scrambled after them and leapt on Harris. Carly heard and then saw her father get tackled, and she skidded to a halt. "Dad!" She rushed back and started hitting and kicking at the hooded man with her robotic arm and leg. Carly kept it up until she was able to knock the person off her father. Once he was pulled up they ran again for the shack, getting in and slamming the door shut. The man banged and clawed at the door for a while before giving up.

After making sure they didn't have any cuts the father and daughter duo took the elevator back down into aperture.

"Well," Carly began, to break the silence, "that was a fun birthday adventure." She grinned at her father.

Harris side glanced at his daughter and sighed.