Doug Rattman was and always had been a creator. His very first memories were of smearing paint across countless sheets of paper. He supposed that was why he had found Aperture so appealing. They didn't just want to discover, they wanted to put their knowledge to the test. All that they learnt wasn't just for some file, it was all to go towards some great invention. They were always searching for the next greatest thing. The next portal gun. He stayed loyal to the facility no matter how bad things got. No matter what he tried to force himself into believing things would get better, yet it would never be true.
He was a follower but in no way an idiot. Unlike the others who had worked on the GLaDOS project he understood that it wasn't going to save them. It wasn't really a knowing, it was a feeling. A deep, unshakeable gut feeling. Caroline could be extremely strong willed if she needed to be but no one was that strong, no one. He wasn't angry when she snapped nor was he surprised. It just filled him with crushing emptiness to know that they had failed to save the one thing left keeping the facility alive.
He always counted himself as alone even though he knew She was watching. He tried to push Her out of his mind, deny Her existence. She never made it easy for him. She filled every inch of the facility with Her presence. Her thoughts and control touched everything, threatening to take over even him. In a desperate attempt to force Her away he filled his little hideouts with the sound of his own rambling. It had got to the point where he found his own voice extremely grating but it drowned out Her as well as his own thoughts of giving in. He wouldn't let himself surrender. Not to Her, not ever. Once he had been told that talking to yourself was the first sign that you're going crazy. He would worry about the last remaining scraps of sanity if he wasn't to busy worrying about someone else's.
Chell was the last person he felt was truly alive. Many of the previous test subjects had lasted a couple of days or so, but they were clearly dead within a few hours. They were just brain dead zombies that wandered around thoughtless and emotionless. They gave up and followed Her instructions until came to an inevitable end. Chell was strong. She was alive and wide awake. He trusted her to stay that way, still he couldn't help be afraid. She had lasted longer than most but what if she couldn't fight it for long enough? What if GLaDOS just got fed up and killed her. He'd seen Her kill to the pettiest of reasons, Chell's determination would send Her temporarily insane.
She was somewhere he couldn't follow now, in Her chamber. He waited patiently in the closest hideout he could find, hoping and praying to a God he didn't believe in. He tried to keep his mind off of his fear by painting. He used the walls to paint a mural to preserve the day victory or the day he finally lost hope.
He snapped his paint brush in concerned frustration. She had been in there for so log. The anxiety made him feel ill. His heart threatened to burst out of his chest, he could hear his pulse thumping in his ears. What if she didn't make it? Had he doomed her? She had been so fast in the test chambers, yet he hadn't heard a single thing she had left them over an hour ago. His mind raced with blinding nerves. He'd killed her. By trying to save her he'd killed her, just like he'd killed Caroline.
The ten minutes Chell was with Her felt like an entirety but it finally past. The resulting explosion shook the room. One of his paint tins fell and permanently stained the floor. He stood in shock for a second, unsure what he was supposed to do. After a few seconds he smiled and sighed with relief. She'd done it. She'd actually done it.
"What was that?" his companion cube asked from the corner.
"The ultimate systems crash"