I've had this idea in my mind for a while now, but I'm not quite satisfied with the outcome... hm... oh well.
Rated T to be safe.

"No! No! Don't do that!"

Wheatley was furious. Absolutely livid. He made a mistake again! Now she was escaping. She was going to kill him. He thought he'd made no mistakes, he'd had those spiked mashy plates surrounding her, thought he'd had no portaling surfaces around, and she was going to be dead. It would all be perfect! He would rid himself of that fatty-fatty-no-parents and that potato, and he would be able to enjoy Aperture like he should have been able to. But no, he just had to go and make another mistake.

He watched Chell as she landed on the catwalk, and she was about to keep running. He begged her not to, he begged her to come back. She obviously wasn't going to, but he'd tried anyway. She was going to get to him, and she was going to kill him. He knew it, and it would be horrible. How could she do that to him, she was supposed to be his friend. As the woman ran away, it hit him. He remembered.

He'd prepared for this. It was one of those moments where he had a good idea, like the idea of shutting off the neurotoxin and replacing the good turrets with crap ones. He'd placed a plate nearby the catwalk, by the edge of the pit he wished she would just fall into.

"Haha! I bet you think you're getting away, don't you, luv? Well, you're not, you selfish, fat, monster of a woman! You are not going to get away!"

With just one powerful thought, the plate flung forward and hit her. Hard. Wheatley could hear the satisfying scream of GLaDOS and he saw the look of horror on Chell's face as she was thrown backwards, falling into the bottomless pit. He let out a victory laugh. Finally, he'd won! He wasn't the moron, Chell was! She was the evil monster who never caught him when he disconnected himself from his management rail, the one who was going to kill him, the one who used him!

Wheatley never used her, he never used anyone in his entire life!

Except the others. Chell wasn't the first one. And you used her, too, for testing. Did you ever think about how Chell felt? You, her only friend, betrayed her, then forced her to test, then killed her. You are a selfish monster.

"SHUT UP!"

It was that stupid voice again, the one in his head, the one that appeared as soon as he entered the mainframe. He didn't know who she was, or why she was there, but he hated her. She wouldn't shut up about Chell and GLaDOS, she wouldn't stop warning him about some "melting core" she'd probably made up. She wouldn't stop scolding him. As if he were some kind of moron.

He never used Chell. Maybe asked her to do a little tests for him, but that was just about it! She was the one who wanted to kill him! He knew it, and that was why he had to kill her first. Before she could get to him. If she was the one who fell from the management rail, he would have caught her. Then again, she was a little thick, so it would probably be a little difficult. That whale of a woman would probably crush him, sort of like a mashy plate without any spikes.

Then again, he was a little heavy. He didn't think of that. Maybe it would have been a little tough on her to blame her for not being able to catch him, and he did sort of throw himself down out of the blue. And maybe it was a little unfair to say he did all of the work and she did nothing? GLaDOS…maybe GLaDOS was right, maybe she did do all of the work. She was the one with the limbs and the portal gun, he would be nowhere without her.

Maybe she wasn't the one who used him. Maybe he used her.

"AUGH! What is wrong with me? I… no.. nonono…"

He'd finally woken up.

"What…what have I done? Luv! Luv, can you hear me?"

It was too late now, he couldn't see her anymore. It was like she wasn't even in Aperture anymore. This time he knew she wasn't coming back. Chell was only human, she wasn't immortal and she wasn't a miracle worker. Well, maybe she was, he'd seen her do some amazing things, but it would take flat-out magic to come alive out of that. Her Long Fall Boots wouldn't do much against a fall like that, she would be crushed.

And who even knew if that pit was bottomless or not? Wheatley surely didn't, all he knew was that it was deadly. And that Chell wasn't coming back.

"Why am I such a moron?"

She was his best friend. And he'd betrayed her, he'd thrown her down a lift's shaft to who knows where, maybe Android Hell itself. And when she'd climbed back up, what did he do? Only throw her down a deadly pit, laughing at her. He was a psychopath.

"…I'm so sorry…"

He didn't want it anymore, the power of controlling the entire facility. It wasn't worth it. He felt crushed, absolutely and utterly terrible. He'd just killed the one person who didn't treat him differently, didn't treat him like a total idiot. And he thanked her by killing her. Oh, what a pal he was!

If robots could cry, Wheatley would be sobbing. All he wanted was to go back, to take it all back. He wouldn't go crazy with power, he would take Chell to the surface, to go see the world and be a normal person like she'd wanted, and he could go with her. And they would both live in a nice little house, and they would just be happy. It was impossible now, unless he could find a way to go back in time.

If only he were like GLaDOS, a robotic genius. He would be able to make that happen eventually, and he would be able to go back in time and stop his craziness. But then again, if he were like GLaDOS, he wouldn't have been in that situation in the first place, would he? He wouldn't have been so stupid.

"WARNING: MOLTEN CORE-"

"SHUT UP!"

Wheatley's voice was cracking. How could a robot feel so much sorrow?

"Self destruction commencing in five minutes."

"I THOUGHT I TOLD YOU TO…"

Wheatley trailed off. What? Self destruct? Five minutes? He'd done it again! Another mistake. And this one was going to cost him, cost a lot of robots, and it would cost Chell, too, if she was still falling and that pit was actually bottomless. It just wasn't fair! He couldn't control his mistakes, he was built that way, built to be a moron and to be full to the brim of bad ideas. Why would those humans do that to him?

He knew exactly why. Because of GLaDOS.

It was then that Wheatley noticed the clock in the back of his mind, one with numbers flashing by faster than the speed of light. One that was counting down his remaining time.

"I hope it's brief and not too painful."

His voice was like a whisper as he wondered what death was like. What came after it? Would there just be nothing? How would it feel if it was that way, just not existing? It made no sense to him, was it possible? If he didn't exist, he wouldn't feel, he wouldn't see… would it not be like being trapped in a dream forever? Thinking about it made him frustrated. Would he move on to another place? If it were true, he was surely going to Android Hell. The thought of the fearful place sent metaphorical chills down Wheatley's metaphorical spine.

"Self destruction commencing in two minutes."

You can still fix it, the voice in his head said. Just press any key. Remember, mistakes can be fixed.

"Well, I can't fix the mistake of killing Chell, now can I?"

Just press any key, you can still save the facility.

"Yeah? Well what if I don't want to? I think I'm done here, little voice. This place and I should just go… in case anything bad happens again."

Wheatley made up his mind. He waited, watching the clock continue, numbers going lower and lower until-

"Self Destruct commencing in thirty seconds."

"Well, this is the end, I guess. I'm sorry that I went mad with power, and I'm sorry I hit you down that lift. I'm sorry I forced you to test and I'm sorry that I killed you, luv. I hope you have fun in whatever place you go after death, but it's surely not Android Hell, so I guess I won't be seeing you again, will I? I'm quite running out of time now. I'm so sorry, luv, I'm so, so, so sorry. But I guess sorry's just not enough, is it?"

"Self destruct commencing."

And then everything went black.