Eli had found a gun, a pistol. It was by the side of a dead security guard he did not recognise. He offered it to Isaac, but the scientist declined it. It was probably for the best. Kleiner was not a violent person and probably wasn't much of a shot. Not that Eli was familiar with weapons either. Unlike the security guards, physicists at Black Mesa did not undergo weapons training upon being hired.

Doctors Vance and Kleiner passed through a great many of the halls, chambers and corridors of Black Mesa, most of which were littered with a slew of bodies and remains, both of alien creatures unknown and facility scientists, many of whom they recognised. The mark of Gordon Freeman's violence was everywhere.

The two scientists meandered through the steel corridors with great caution. They assumed that what alien creatures there were had teleported to Black Mesa all at once at the climax of the resonance cascade, at the very moment the exotic matter had been pushed into the anti-mass spectrometer. They were wrong, however. The aliens had never stopped materialising.

Shortly after Eli had acquired a pistol, a flash of green appeared in a hallway, directly behind the two scientists, then vanished, leaving only a headcrab in its wake. It crawled toward them slowly, awkwardly, as if wasn't used to its own weight. Perhaps the gravity of its own world was less taxing. Nonetheless, Eli and Isaac backed away slowly, the creature advancing ever closer. Eli aimed at it carefully. He had never fired a gun before. In spite of that, he felt it couldn't be difficult. He pulled the trigger and there was a brief blast and knock-back. The bullet struck the ground just to the left of the creature's hind leg. Eli aimed again, this time to the right. Fired again. Another miss.

'Eli', said Kleiner, an anxious warning in his voice. 'We should move back. It's getting closer.'

Both were sure those hind legs would launch it high into the air, straight at them, but Eli was determined. This time he would hit it.

He was wrong. He had miscalculated. Before he could fire the crab jumped and Eli jerked himself back with fear. The gun went off, and in a second Eli was on the ground, fully expecting to feel the weight of the creature as it wrapped itself around his head, but looking up he could see it lying inert on the ground, its green blood splattered around it. He had shot it in midair.

Isaac let out a shaky breath.

Eli cursed himself for his stupidity. That had been far too close. But he had to learn how to kill these things. He would get nowhere by avoiding violence, especially now that Black Mesa was filled with things that wanted to kill its scientists, security guards, and civilians.

'Eli, you have to be more careful', said Kleiner. 'You could have died. I hope you'll refrain from using that pistol from now on.'

'No Izzy, that's precisely the opposite of what I will do. There are deathtraps in the form of these aliens all over the facility, and I wager that most of them will be far more dangerous than these head-suckers. Things are harder for us. We aren't wearing hazard suits like Dr. Freeman is. We have to be extra careful. Death could be around any corner. You should learn to use a weapon, same as me.

'Eli, you know I'm not a violent man…'

'Nor am I, but we don't have a choice.'

'But what of rescue? Surely Dr. Breen has called in the military to save us.'

'Perhaps, but nothing is for certain.

'But you said yourself that things are harder for us than they are for Gordon. Isn't it wiser to wait down here and hide from the aliens until the military arrives?'

'If I had only myself to worry about, yes, but Azian and Alyx are somewhere in this facility. Every second I'm away from my family it becomes more and more likely that they are endangered. I have to find them. I won't hold it against you if you decide to find a hiding space and wait, Izzy, but I can't stay here.'

Anxiety streaked across Kleiner's face. His morals fought with his baser instincts. He would have liked nothing more than to find some out-of-the-way test chamber, a secluded office or even a dumpster to hole up in. Isaac Kleiner was not a brave man. But if he left his best friend right here to traverse the considerable space of Black Mesa alone, he could never forgive himself.

Kleiner ran his fingers through his scanty hair apprehensively.

'Alright, Eli. I'll go with you.'

'Thank you, Izzy. Things would be simpler if the transit system was functioning – we could go straight to the dormitories – but it must have shut down sometime after the evacuation alarm went off. We'll have to find another way.'

Things did not get easier for the pair, and they weren't lucky enough to find a second discarded pistol. In any case, Kleiner was glad to leave the shooting to Eli, whenever necessary. Denied the transit system which connected the Sector C Test Labs to Level 3 Dormitories, and many other places in between, they had to follow the trail of corpses left by Gordon Freeman.

In doing so, they learned much about the fauna of the hostile border-world, encountering more corpses of the zombie-like creatures created by the fusion of headcrab and hapless scientist, but also things which were more bizarre, if that was possible. One chamber was littered with creatures around the size of small dogs, with three legs, a ridged back and several large, beady eyes clustered together in its round face. Its bumpy flesh was the colour of curdled milk.

Once, as they passed over a catwalk looking over a storage area of several crates and a wide basin of radioactive waste, they glimpsed the largest life-form they had seen yet. This one was bipedal, and yet crouched low in the pool of waste it seemed to be comfortable in. What appeared to be its face was covered with several red tentacles splayed out in all directions, almost starfish-like. Its beige body was dappled with dark blotches. Eli and Kleiner looked down on it for some seconds until it seemed to detect them. It tensed up, then let out a blob of saliva which shot up from below, striking the floor of the metal catwalk just below them. The sputum hissed as it corroded the steel and the two scientists hurried on, Eli deciding not to waste his bullets on the creature.

When they had reached an area which seemed relatively safer, Kleiner said: 'I suppose we should start giving these life-forms names, assuming they haven't been named already by our colleagues. I wonder what will become the accepted terms for these species.'

Would seeing these animals be a regular occurrence from now on? Eli mused inwardly. Would sighting them become commonplace after today? It was a strange thought.

Thankfully, the teleportation of the aliens was few and far between, at least in close proximity to Vance and Kleiner. It seemed most of the organisms had materialised when Gordon had passed through, and now that they had probed into Black Mesa and found this area hostile enough to kill them, whatever intelligent species in charge of teleporting them in had decided that doing so wasn't worth it, at least in this sector. Most of the organisms they did come across had been laid to waste by the physicist in the hazard suit, though they passed a great many human bodies as well, nearly all scientists.

After over an hour of wandering, hopefully, in the direction of the dormitories, the pair heard something that made their hearts lift. Human voices, and certainly not those of scientists.

'Check in.'

'Squad, all hostiles clear.'

Eli and Isaac, standing on a mezzanine, had come upon a warehouse filled with crates. The voices were coming from below them. The phrases they used sounded like military jargon, and that could only mean that rescue had come for the scientists of Black Mesa.

Dr. Kleiner was about to cry out with relief and dart down the stairs to meet his saviours, but Eli held him back with an arm across his chest and a finger on his lips for quiet. Something felt wrong.

'If the soldiers are here to rescue us, then why can't we hear any scientists among them?' whispered Eli.

'Maybe they've already been sent to the surface', supplied Kleiner.

Eli silently laid himself prone next to the edge of the walkway they had been standing on and peered over the edge, and down. The warehouse was spacious, and crates weren't the only thing littered all over the storage area. There were dead bodies, something Eli and grown accustomed to surprisingly quickly since the crisis had begun. In between boxes were the cadavers of both labcoat-wearing scientists and camo-wearing marines. The odd thing was that Eli saw no sign of foreign entities. Judging by the bullet wounds and human blood it was clear that the only violent party here could be human: either the military, Gordon Freeman, or both.

Eli could see that two soldiers appeared to be combing the area.

'Fuck. What a mess', said one. 'You said one guy did all this?'

'One guy. A scientist. There was only one survivor from squad B. He died of his wounds a little after we found him. He said they were purging the area of these dumbass scientists, like we were told to. Not a single one fought back. Most either pleaded for their lives or were shot in the back running away. Then this guy comes out of nowhere in one of those orange suits you wear wherever there's radioactive waste. He uses the element of surprise in an ambush, using one of our shotguns one minute, then a submachine gun in the next. The survivor told us the scientist used the crates here for cover, and bullets would ricochet off his suit whenever he was out in the open. It was as if he was a man possessed, like some demon was working through him.'

The second soldier spoke: 'With everything I've seen today, alien monsters and all, I wouldn't find that hard to believe. Maybe this guy is in league with the aliens.'

'Maybe. But I'm getting the feeling I wouldn't mind coming across this bastard. Since we got here all we've been ordered to eradicate are chicken shit scientists and floor-crawling head-humpers. I wouldn't mind an opponent with half a brain, someone who really fights back. Besides, we need revenge for Squad B.'

'Do we know this guy's name?'

'The survivor of Squad B said they were questioning some scientists just before the guy struck. Said his name was Gordon Freeman.'

'Damn stupid name. Sounds like some ordinary guy. Not someone who could wipe out almost an entire squad.'

'We'll get him eventually. I just hope I'm there when we do. One scientist can't take our entire fighting force, hazard suit or no hazard suit.'

Eli pulled himself silently away from the edge. He had learned two important things. First, the military was not there to evacuate them. Now he knew that their presence would make it doubly hard for him to ensure the safety of his family. They now had aliens and soldiers to worry about. If they would kill scientist employees, they would probably kill civilians too. They wanted all knowledge of Black Mesa and the work that went on there to be wiped clean.

The second thing he now knew was that Gordon was still alive. If the rumours he had just heard from the soldier grunts were true, he had become a one-man army, resisting both alien creatures and trained marines. That couldn't have been down to the defence provided by the HEV suit alone. Gordon was a fast learner, they knew that already. He had learned to use whatever weapons he had come across with aplomb, besting even marines trained to use them. Did the young scientist have more on his side than just versatility? And what of the grey-skinned, suitcase bearing man from before? Both of these men were mysteries. Could it be that they were connected in some way?

Eli turned back to Dr. Kleiner, who was huddled against a concrete column, his knees drawn up into his chest. He was an anxious man at the best of times, but the slew of dead bodies everywhere and the danger around every corner really seemed to have got to him. Eli knew exactly how he was feeling, however, he had something Kleiner didn't have, a family that needed him. It was that emotion, that hard necessity, that drove him on, forcing him through the perilous facility. They might need him at this very moment, they might be safe, they might even have been killed. Eli forced the latter thought from his head. It would do no good to think that way.

Kleiner broke through his reverie with urgent, whispered words: 'Eli, I know this warehouse. There's an elevator just up ahead. It leads to the surface. Once we're there we can search for Azian and your daughter if they've been evacuated, and if we don't find them there, then I'm sure there'll be some passage which leads back down to the dormitories.'

'Alright', said Eli. 'But we don't have the protection of hazard suits like Gordon does. Our only option is to use stealth. With luck, the marines will be preoccupied with the aliens and other scientists who are still assuming they are about to be rescued.'

'Those poor fools', muttered Kleiner under his breath.

Eli belly crawled to the walkway's edge once more and looked down. The two soldiers had finished surveying the corpse-littered area and seemed to be awaiting orders next to a thick steel door at one end of the narrow warehouse. On the opposite end, Kleiner indicated, was where they would find the elevator. To get there they would have to climb down a steel staircase to the ground floor which would undoubtedly create noise.

Eli soundlessly slipped off his shoes, and Kleiner, seeing the sense in what his friend was doing, did the same. They started to step down the stairs, hoping that the soldiers would not look up. It seemed they had no reason to. Now and then they would hear a report on their radio, then one of them would respond. At least their attention was diverted.

After what seemed like an age, the two scientists reached the ground level. The place was bestrewn with tall crates which thankfully blocked the soldier's line of sight in most places. Now that they were here, Eli and Isaac could see the dead corpses and wide pools of blood up close. They had seen dead bodies already on the way here, but not on this scale. The soldiers seemed to be even more brutal than the aliens had been. Bullets had torn through science team lab coats and everything underneath. Heads had been smashed by high calibre rounds and bones had been fractured, leaving their limbs stretched out at odd angles. Eli wondered whether, even if he could see their faces clearly, would he recognise these people?

The only living scientists in the warehouse tiptoed around the dead matter which surrounded them. At one point Dr. Kleiner accidentally stepped into the edge of a pool of blood, still lukewarm, and almost cried out in surprise and disgust, catching himself at the last minute.

Eventually, they found their way to the elevator where Kleiner said it would be. It's hard metal surface was ridged. It was large, clearly intended to provide space for a forklift and its cargo.

Now came the dangerous part. Pressing the elevator's button and having the platform ascend would undoubtedly make noise. Would the soldiers at the opposite side of the warehouse come and investigate? And what of the surface? For all they knew they would be climbing into a marine-filled area and would be shot on sight.

Vance and Kleiner both drew in a breath, then pushed the button. The lift started to move up. The rasping noise it made was agonising, but they heard nothing from the other side of the warehouse. Most likely the two soldiers they had eavesdropped on had strict orders to remain where they were.

The elevator was reaching the top. The two scientists had half expected to find more marines standing guard at the surface level, but all they encountered was gory evidence of Gordon Freeman's passage. Though Eli was Dr. Freeman's colleague and would have even gone as far as to call the two of them friends, he could fully understand why the grunts hated him as much as they did. He had killed not only their fellows, but most likely many of their friends. Not that Eli pitied the incoming military. They had thrown the first stone and slaughtered defenceless scientists as if it was nothing. That was unforgivable. At the same time they were in awe of Gordon too. Eli could understand that from the tone of voice of the two men he had overheard. Eli found that he shared that sentiment.

They stepped out onto an aboveground warehouse. Eli was relieved beyond measure to see the sun after spending so long in the sterile, steel corridors of the lower facility.

The two of them put their shoes back on.

'The Level 3 Dormitories are southwest of the Sector C Test Labs', stated Dr. Kleiner. 'It shouldn't be too difficult to determine what course we should take.'

It was still morning, and the sun was quite low in the east. From that, the two physicists judged roughly in what direction they should head.

The spaces on the surface of Black Mesa were much more expansive. The ground was red sand and gravel. The military had certainly moved in with everything they had. There were army jeeps and sandbags piled high to act as defences. Not that it seemed it had done the soldiers much good. The outside of the warehouse was just as corpse-littered. There was even a beige coloured tank, the turret of which was mangled and smoking.

Kleiner drew in a breath sharply with surprise. 'Did Gordon do all this?'

Eli spied something slumped against a bullet-ridden sandbag and padded over to get a better look. His suspicions were correct. There were more hostile alien life-forms than the head crabs. The creature before him was also bullet-ridden, its blood a yellow-ochre. It must have been taller than him, taller than most humans, but somehow it was also squat and quite muscular. A third arm protruded from its chest, and its feet, shoulders and head were covered in smooth, dark metal. It had three small red eyes and a mouth that was vertical and lined with thin, sharp fangs.

His interest overpowering his fear momentarily, Kleiner approached the corpse. 'Fascinating. Eli, do you think this is what the aliens directing the invasion of Black Mesa look like? Most organisms we have come across today are no doubt mere animals, but this creature looks almost humanoid: limbs, torso and head…'

Eli's attention was elsewhere. Discarded on the ground next to the monster was something he took at first to be another limb, similar as it was in shape and colour to the dead alien. Picking it up, he found it had a hollow on one end which was obviously meant for a hand much bigger than his. Within was what felt like a trigger. As soon as he pressed it a sharp squeal sounded which made both Eli and Isaac jump, the latter now remembering his apprehension.

Something around the size and shape of a hornet shot out, leaving an orange streak in its wake. The insect shot around a corner, curving in the air, narrowly missing Dr. Kleiner. The two men heard a muffled squelch, the sound of something hard piercing flesh, and then a guttural outcry. Something was still alive in the area. Could it be another three-eyed giant?

Eli passed the bulky weapon to Kleiner, raised his pistol, then slowly and silently crept towards the edge of the concrete corner. He took a breath, then in one rapidly movement swung around the corner. The scene he saw was much the same as the one they had just traversed: sandbags, cemented walls, red gravel. But there, lying on the hot ground, unshielded from the pitiless New Mexico sun, was another alien.

It was somewhat like the other in shape: humanoid, with an arm protruding from its front. But this one bore no armour, its skin was smoother, and its head on an elongated neck craned forward instead of being pressed into its shoulders. Four teeth jutted down from a downturned mouth. There was an odd, collar-like object around its neck. It looked heavy. The most striking thing about the creature, Eli thought, was its eye, which was a deep, penetrating red, and was blinking at him in a way that seemed weak and fearful, as if it was begging for clemency.

Memories from dreams Eli had had only that morning surfaced in his mind. He had the vague notion that this creature or some of its fellows had featured in his nightmares, but why?

Eli aimed the gun at the alien for some seconds, then slowly lowered it as he became convinced it was no threat. The thing was sprawled, and Eli noticed it had been shot several times in the leg and torso. Unless the alien's species was much hardier than that of the human's, it was most likely dying. Jutting from its shoulder was the insect Eli had fired from the weapon.

Isaac Kleiner crept around the corner once he realised that Eli was not in danger, and gasped again when he saw what Eli had discovered, his fascination having returned.

'This thing is dying', said Eli to Kleiner. 'I suppose the least we could do is put it out of its misery, even if it is hostile.'

'Wait', uttered Kleiner. He moved closer to the dying creature. Knelt beside it.

'Can you understand me? Can you understand what I'm saying?'

The alien turned its large eye to Dr. Kleiner.

'Do you know what I'm saying?'

'Izzy. It doesn't—'

'Their slaves', rasped the alien, green blood bubbling from its mouth as it did so. 'We are their slaves…we are…'

Both scientists jumped back in surprise.

'Win…you cannot win…you cannot…'

For some strange reason, Eli got the impression that these words were not the alien's. That perhaps it was being made to say this by some other entity. Why was it shackled and collared? Were the alien and its kind being forced to attack the humans of Black Mesa?

It did not matter now. After the final few sounds passed from the alien's maw, it slumped back onto the gravel, all consciousness leaving its great eye.

The two scientists stood in silence for some time, then Eli said:

'Now we know there is intelligence in the creatures invading our world. They aren't just vicious animals being sent in to slaughter us. This was planned, and planned carefully. Where there's one intelligent alien, there's another, and I get the feeling that not all of them have been forced into this invasion like this one was.'

'Is see no other attackers, Eli', said Kleiner. 'We cannot delay. Let's continue and look for a passage down to the dormitories. I'm sure Alyx and Azian are waiting for you there.'