A/N: I actually had this written up for awhile, but finally decided to go ahead and post it. There will, in fact, be a Part 2 coming along, though I cannot say for sure how quickly. But, anyway, enjoy!

Ah, and, disclaimer: Obviously, I don't own Half Life, or any of its characters, though the random side character I've thrown in is mine. If Valve wants him, though, they are welcome to him. :)

Someone was crazy, that was the only possible explanation for this, and Barney wasn't sure if it was him. After all, if there was any justice in the world, he should have been at home, relaxing on the couch with his girlfriend. And a beer. Maybe, if justice was feeling particularly generous, they'd be watching one of their favorite scary movies, and Lauren would cuddle up next to him and squeak in adorable terror at the appropriate moments, and he'd put his arm around her... Yeah. He really wished he was home, watching a scary movie. Instead of living one.

Why. Why was he crawling around in the vents, in the middle of the freakin' night? Whyyyyy.

"Whoever designed these things should be shot," he grumbled, trying to crawl and hold his flashlight and his handgun at the same time. The handgun was an important part of this plan, because if it was some mutated rat monster that escaped from a lab somewhere, he was going to be prepared, dammit. At least it wasn't that dusty. Just dark, and cramped, and windy, with tons and tons of places for small, mutated monsters to potentially hide. Not that there had actually been anything in here so far. But he'd seen scuff-marks in here that someone---or something---had left. He had no idea if they were fresh, but, to be perfectly honest, if this all turned out to be a wild goose chase and he didn't have to deal with some horrible rabid beast that had got into the vents and was now waiting to leap out of the darkness and eat his face, Barney would not mind at all.

Normally, the night shift wasn't all that bad of a gig. He'd actually volunteered for it, more often than not. The scientists who were dedicated enough to stay in their labs this late were, oddly enough, actually more friendly than the ones Barney had to deal with during the day shift. Of course, there were some exceptions (coughMagnussoncough), but overall the night crew was, in Barney Calhoun's personal opinion, the best of the Black Mesa science team. Except when they dumped things like this in his lap.

Okay, okay, so, this was probably in his job description somewhere. And he couldn't really fault them for getting spooked: The whole place was quieter than it was in the daytime, emptier, and darker, and suddenly they were hearing something moving around in the vents. And of course that meant that he had to go and take care of it. He knew he'd never catch one of the brainy science team crawling on their hands and knees through the air ducts.

Which was why, when he turned a corner a few seconds later and his flashlight illuminated a squinting, bespectacled Gordon Freeman, Barney yelled and only just managed to avoid reflexively firing off his handgun and accidentally shooting his best friend in the face. "Jesus! Gordon!"

Gordon didn't actually say the words "Who did you expect?" but he didn't have to. His expression clearly conveyed the message.

Barney slumped back against one side of the duct, and glared. "You gave me a friggin' heart attack. What are you doin', crawling around in here in the dark?"

Gordon held up the object he had been fiddling with when Barney interrupted him. It was a flashlight, though it wasn't living up to its name. Apparently the bulb had burnt out.

"Okay," Barney growled. "Lemme rephrase that: What. The hell. Are you doing. In the air ducts, Gordon?!"

There was an itty bitty quirk to the corner of the scientist's mouth, but he managed to keep an otherwise straight and sincerely apologetic expression. "I'm... exploring."

Barney stared at him. "Exploring."

Gordon nodded.

"You're. Exploring. The air ducts. In an underground science facility. In the middle of the night."

A raised eyebrow suggested that, indeed, this was all true, and now Gordon was waiting for the punch line.

Barney didn't disappoint him. His scowl turned to one of mock indignation. "And you didn't invite me?"

The peculiar thing about Dr. Raymond A. Peterson was that, unlike Barney Calhoun, he had no imagination whatsoever. Certainly he was brilliant, otherwise he wouldn't have been hired by Black Mesa in the first place, but his strengths lay in clear, logical problem solving, rather than in abstract thinking. Once a problem presented itself, he could usually work out the simplest, and most efficient manner of dealing with it. And, while it wasn't as though he couldn't extrapolate potential consequences to various actions or effects, he didn't come up with illogical or whimsical explanations.

This is why, when he was distracted from the small experiment he'd been running in his office by a soft shuffling sound coming from somewhere above him, he did not jump to any conclusions, supernatural or mundane. There was no data. A quick glance up revealed nothing but the ceiling, and an air vent that was mounted in it. The shuffling got louder. Dr Peterson looked down at his experiment, and then back up at the vent, torn between investigating the noise, or ignoring it and continuing with his work. He supposed he could summon a security guard to investigate it, but that would probably keep him away from his experiment even longer than if he investigated it himself.

Making up his mind, Dr. Peterson cleared his throat, and called, "Err. Hello? Is anyone there?"

The shuffling stopped, but otherwise there was no answer.

He tried again. "Ah, I can hear you moving in there. Its rather distracting. If you can understand me, then I'd appreciate it if you could be a little quieter. Also, if you could tell me what you are, assuming you possess the capability."

Still nothing.

"Well, obviously you do not." With a shrug, he picked up a chair and moved it under the vent. Carefully, he climbed up onto it, and then discovered he had to stand on tip toe to see into the vent itself.

He did so.

And then he screamed.

"Y'know, Gordon," Barney commented, dryly, as his helmet banged up against an unexpectedly low part of the ceiling. "I really wish I could see where I'm going. Do you think maybe you could shine the flashlight somewhere, oh... useful?"

The flashlight (which, Barney was sure, was a freak of nature and refused light up anything in a logical way, instead picking spots of vent at random) did not give him enough light to see Gordon's expression, but it didn't have to. Barney's imagination was more than capable of translating the icy silence into a Freeman Death Glare.

He was just opening his to retort when the screaming started. Much later, he would look back and be rather proud of his finely honed security guard instincts, which had him scrambling towards the source of the screams before he could stop and consider what a horrible idea that was. It sounded close, though since it was echoing through the ventilation system, it was kind of hard to tell. It wasn't hard to follow, however.

They rounded a corner, and found they could actually see. Light was coming through the grille of a vent, that seemed to open into an office. The screaming was also coming through this. And, as they approached the grille, they heard the sound of running footsteps, and a door being opened.

"Raymond!" Dr. Vance's voice drifted through the vent. Barney peered through the grille just as Eli knelt down next to the terrified scientist and put a hand on his shoulder. A couple of other scientists hovered nearby, looking anxious and concerned. " Good God, man, are you all right? What were you yelling about?"

Dr. Peterson, who was cowering against the far wall, pointed a trembling finger at the very vent Barney was peeking out of. "Something... In there."

Eli glanced up at the vent, and recoiled, seeing movement behind it. "What th-"

"Hey, whoa, it wasn't me, Doc. I just got here."

The older scientist frowned, squinting up to try and see through the angled grille. "Barney... if this is some kind of prank-"

"No!" Everyone turned to look at Dr Peterson, who was still starting at the vent with wide eyes. "It was a monster."

There was a moment of silence, then Eli turned to look up at Barney again.

"Uh, it really wasn't me, Doc. Some of the other scientists were sayin' they heard some noises up in the ventilation system, so I was checkin' it out." He shot a glance at Gordon, and added, "I thought I'd figured out what was making the noise, but... uh... I guess not."

Eli rubbed his chin, and then glanced back down at the trembling Peterson. "I suppose you'd better check it out, then. Its probably a rat, or something..." He trailed off, realizing that this rationalization was weakened by the fact that this was Raymond he was talking about. The man just simply did not overreact to anything. Eli just couldn't imagine what might have scared him so much, and frankly, he didn't want to. "Keep us informed."

"Not a problem, Doc. Make sure Dr. Peterson's okay, would ya?"

At Dr Vance's assurance he would, Barney sat back from the vent and glanced at Gordon, then nodded down the duct, opposite the way they'd come. "Only way, uh, whatever it was could have gone."

As he turned and started to make his way along the vent, he caught Gordon's skeptical expression out of the corner of his eye. In a low voice, Barney explained, "This is Dr. Peterson. He's got the overactive imagination of a rock. A really dull, boring rock. If he says he saw something, then he probably did."

When Gordon's skeptical expression didn't fade, Barney persisted. "Aw, c'mon. We're in an underground research facility. Do you know everything that's going on down here? Maybe something escaped, got into the vents."

Gordon still didn't look convinced, but he merely shook his head in resignation and murmured, "Too many scary movies, Barney."

"Hey. There's no such thing as too many scary movies."