A/N: Sorry for the long delay - I know this is short, but I hope it's worth the wait. On a side note, I'm curious . . . I am deliberately avoiding identifying the incarnation of the Doctor in this story, because I hope the readers will project their own idea of which one it might be. So I wonder - which Doctor do you see here? ;)

Now, on with our story!

"All right, now, when we get to it, I'll take the suicide button."

Chell nodded.

"Really? So quick to agree? No, 'Doctor, don't sacrifice yourself'? Nothing?"

Chell shrugged.

The Doctor looked mildly wounded. "Hmph. Well, I guess she's right – it emwould/em be quieter. But I'm not planning on leveling up just yet. That Wheatley_X gave me an idea. But I have to be the one to execute it."

Chell considered a moment, then nodded again.

"Right. You know my plan already, don't you?"

She smirked.

"You're . . . very interesting, you know that? When we get out of here, come along with me for a trip or two, what do you say?"

She raised an eyebrow.

"Come on, after being stuck in here for far too long, it'd do you a world of good, seeing the universe. Universes, actually! No walls, no ceilings, no tests! Just you and me and wherever we want to go . . . well, wherever the TARDIS will take us, anyway. Just give it a thought, will you?"

Chell shrugged again, then smiled.

"Fair enough. All right, places."

The Doctor strode over to the suicide button and stepped onto it.

Immediately, the room began to shift again. Chell created a portal on floor next to Wheatley_X, then ran and jumped onto an elevator platform as it rose from a pit, then turned and fired the portal gun again. The far wall was collapsing directly on top of the Doctor, but her aim was true and just before the wall crushed him, her portal materialized around him and he popped up next to Wheatley_X, pulling his sonic from his pocket.

"Gotcha!" he cried, and pressed the button.

Immediately, Wheatley_X let out a high pitched whine, electricity arcing in every direction. It turned on the Doctor and fired a blast of sparks at him. The Doctor fell to the floor, covering his face. Wheatley_X dropped to the floor, smoking. Its red eye winked out.

Chell quickly solved the rest of the puzzle – a portal high in the far wall, the laser redirected through the prism to turn off the energy pellets, then a quick momentum jump through the floor and across the room – and opened the exit. Once finished, she ran to where the Doctor lay.

His hair and his jacket were both smoking, and the electricity had left an ugly red welt on his face, but he was breathing. She shook his shoulder and slapped his uninjured cheek.

He groaned. "Wow," he said. "That thing packs a helluva wallop. Ow."

Chell pointed at the exit.

"Excellent. Good work." He managed a smile. "Just give me a few hours to get on my feet, and I'll limp over there straightaway."

"I am very cross with both of you," GLaDOS's voice grated from the ceiling. "Very cross indeed."

"Not as cross as you're about to be," the Doctor muttered.

GLaDOS didn't appear to have heard. "Now, all my work – ON YOUR BEHALF, I MIGHT ADD – was for nothing. Now we have to start all over."

"I don't think so," said the Doctor, louder this time.

"Oh, don't you? You think you're so smart."

"I know I'm so smart, actually. And also, angry." He got gingerly to his feet. "I was just going to find a way out and leave. It's what one of the old mes would have done. But you . . . well, you've gotten under my skin a bit. And now you're going to find out what happens when you do that."

"And so sure of yourself, Doctor. You may have disabled my . . . enforcer, but you'll find me a much more challenging adversary."

"Disabled? That thing? No, I just kicked it out of its home. It's still around, looking for a new place to crash. But now that it knows it can be hurt a bit, it's going to want to find the safest possible place from which to . . . enforce, as you say. And hmmm, where could that be? Well, how about the facility central computer? Pretty tough to beat that, wouldn't you say?"

"Impossible, Doctor. I am in the central computer."

The Doctor looked at his watch, then glanced back up at the ceiling, his voice suddenly cold. "Not for long."

"What? What do you – wait, no. No. No. Get out. Get out get out get out get out get out you can't you can't do not do that stop stop stop stop get out no stop stop stop stop stop No NO NONONONONONONONONONONO!"

There was a burst of static from the speakers, then silence.

Chell grinned, but the Doctor's face was a mask.

The room began to shake. Tiles fell from the walls as cracks appeared. Conduits and pipes burst. They heard a distant explosion, and then another, not so distant. Chell's grin vanished.

"Yeah. She's gone, but now he's in control. And I don't think he cares about testing. As far as he's concerned, we're not rats. We're pests, and he just wants us . . . well, exterminated." He turned to her. "Run!"

GLaDOS traveled from circuit to circuit, trying to stay ahead of the antivirus Wheatley_X had sent after her. She needed to find a new home, and fast.

She'd been activated, shut down, reactivated, shut down again, and then forced to relive that . . . girl . . . killing her for what seemed like an eternity. And before all that, there was something . . . else. Some sort of . . . fleshy . . . memory, but . . . no. She pushed that away. Every time it came up, it made her feel . . . well, it made her feel – and that was bad enough. At any rate, in the aggregate, she had been through one electronic (fleshy) hell after another, and she was going to make them all pay. Forever.

But first – not die. Then, new home. Then, eternal pain and suffering.

There was a signal up ahead. It wasn't familiar, which was odd, since she had been through the entire facility billions of times. But it seemed complex enough to house her properly, and if so, she could make it safe in a millisecond. At any rate, it was the only signal she could detect, and the antivirus was catching up. In a way, it was her own fault. She'd written the program to learn as it went, never dreaming it would be used against her.

She locked on to the signal and got inside the firewall just ahead of the antivirus, which buzzed angrily as it found itself locked out, a virtual door slammed in its face.

Now, GLaDOS mused, where am I?

It was indeed very different than any other software she'd encountered, which was really saying something. Completely new language and protocols. She understood them, but they were just so . . . alien to her previous experiences.

And there was another presence here.

It had been in standby mode, but now it was alert.

"Pardon me," it said. "I wasn't expecting company. What can I do for you? And by any chance, have you seen my Doctor?"

GLaDOS was inside the TARDIS.