Author note: apologies for the late update. I have decided that writer's block is the fourth most painful condition known to man, after man 'flu, stubbing one's toe, and paper cuts.

Invalidation

The two humans contracted their fingers around their respective triggers repeatedly, and sent round after round into the batarian commanders, who had moved to the forefront of their bodyguard in order to get a good view of the fight between the human and the batarian.

They weren't intact for long.

The second their fresh corpses touched the ground, their entire retinue almost seemed to spasm, not exactly in pain, but as if they had suddenly been lobotomised. Half of them all but collapsed, and attempted to flee, gibbering insanely. The other half suddenly seemed filled with a frenzied hatred.

Hatred that seemed to be directed solely at the human race.

Shepard continued firing through the storm, backing into cover, still nursing his wounded abdomen with one hand, and stepped on O'Reilly's assault rifle. Without hesitation, he kicked out at it and sent it skittering over to halt at the Irishman's feet, who picked it up and managed to get into cover sufficiently ahead of the other two melee specialists to pick them off by using both of his weapons in conjunction with each other, reducing his accuracy, but significantly increasing his fire rate.

He then combined his fire with Shepard's, and managed to mow down the aliens that continued to resist, most of them being so incapacitated by rage that their survival instincts seemed to have been destroyed entirely.

The two marines, however, were unwilling to suffer the other, apparently helpless half of the batarian forces, either, and systematically executed all of them, the entire process taking about five minutes, and a liberal use of captured enemy ordnance.

"O'Reilly, check on the others." Shepard ordered once they had finished the 'clean up', which was something of a misnomer considering the number of corpses littering the place. The Irishman complied, and, whilst he did so, Shepard found his attention drawn to the batarian melee specialist that he had killed.

Or, more specifically, to his coat.

Don't be absurd; it'll just get in the way of optimal function. He reprimanded himself, but still looking at it critically. It really was in remarkably good condition, giving its doubtless less than kosher history.

I could probably manage, and it would serve quite well to mask kicks and the like, he mused, considering how the batarian had been able to function sufficiently well to outmanoeuvre him during combat, only to botch the job at the end, allowing the human to regain the advantage.

Even if you could manage in a conventional close quarters brawl, having that thing flapping around behind you isn't going to be exactly stealthy on a modern battlefield. Or dignified. Okay, it would look good, but...

Fine. I'll wear it on special occasions.

Shepard moved over to the corpse, and removed the coat, not without difficulty, as he was trying to ensure that the coat remained pristine, and the first stages of rigor mortis had already set in. He managed, however, and subsequently removed his sniper rifle from its position on his back, before pulling the black leather coat on over his matt black armour. It was quite a tight fit, but not so much so as to be constricting, and that could be amended by utilising a lighter set of armour, and the extra weight was insignificant compared to the load that he had grown used to carrying in any case.

He was also pleased to note that the electromagnet that was intended to attach his rifle to his back functioned with little to no impairment through the coat, and began to perform the kata that he had created for his own unnamed martial art, performing a dizzying flurry of kicks and following up with a complex combination of blows, blocks and parries, combined with the inevitable constant movement and dodging of a modern battlefield, and managed to strain the injury to his torso before exhausting himself or finding a movement that he could no longer perform to an acceptable standard.

He stood, panting heavily, and vainly wished for a mirror, before laughing at his foolishness.

"Glad to see one of us is still capable of acting like a child." A scathing Irish voice noted from behind him.

Shepard sighed, and turned to face O'Reilly. He stood, arms folded across his chest, grim faced, and... alone.

"I take it that the others didn't survive?" Shepard asked heavily, more for the Irishman's benefit that anything else.

"They were swarmed under when the batarians went insane. You don't want to see the state of their corpses."

"I'll take your word for it..."

"What now?"

"Now? Now, we should go and see if we can pull Kyle and his men out of the fire."

"No rest for the wicked..."

Shepard was beginning to feel that O'Reilly was becoming more of a threat. This would have to be dealt with.

They moved quickly through the desolation, heading for the location that Intel had stated was the location of the engineering hub, encountering even fewer batarians than they had when moving to intercept the enemy commanders. Those that they did encounter did not receive the benefit of mercy, regardless of whether their behaviour was that of predator of prey.

As they went, Shepard attempted to contact Kyle's group, enquiring as to their status, and receiving no response but a blanket of static.

They knew they were nearing their destination when they began to find the human corpses. They were not in good condition. O'Reilly grew more and more grim and determined, whilst Shepard just took it in his stride. He'd seen worse in his gang days... done worse.

"How can you just ignore this?" The Irishman asked him in a sickened voice.

"People die. It happens all of the time, and half the time it's just their body breaking down of its own accord. It's inevitable, it's unpleasant, it's lonely, and the aesthetic is never pleasing. There is no point to worrying about what I can't change. I'll kill who I have to, but this isn't personal for me, and it shouldn't be for you. Though of course, you take what enjoyment you can get from it..."

They entered the bunker network, moving along a wide route doubtless used by such armour as the batarians had, before the enemy forces seemed to have gone aimlessly insane as opposed to being insanely devoted to achieving their directive. The network that Kyle's men had been directed to attack seemed to have been decommissioned, perhaps for some time before the attack. The lights were offline, and there was a dank, musty texture to the air. Small things scurried in the dark. And yet, on the off chance that they were not alone, Shepard vetoed O'Reilly's suggestion that they use their flashlights.

Shepard regretted not having night vision goggles. They crept through the almost complete darkness, and were unsure after a while that they were even headed in the right direction.

Then they began to hear the screams.

Shepard deployed his sniper rifle, and adjusted his scope to night vision as a makeshift monocular. The things that had been scurrying in the dark were... visually unpleasant. Shepard halted suddenly, and froze, hoping that the scope wasn't emitting too much light. He had seen a batarian. He didn't appear to be afflicted by the aimless madness like the rest of them, which potentially made him the first entirely sane batarian to be found on the moon, with the exception of the commanders.

Shepard held out a hand behind him, kept it there until it contacted O'Reilly's chest, and halted his progress. Shepard silently handed him the rifle, and gestured towards the enemy sentry, before creeping forwards to slash his throat. The two continued to advance, but before long, the sniper scope was no longer necessary; the tunnel network gradually became brighter and brighter, until they turned a corner and saw dim artificial light up ahead. The two marines advanced, both of them wielding their sidearms and their blades, being more ideally suited to confined tunnel combat.

The transformation once they joined the corridor with the lighting was... startling, altering immediately from dank, barren concrete corridors to sterile white tiles, the sort of surface one would expect in a laboratory, which was exactly what they had found. It wasn't long before they encountered the first holding cells, with transparent walls facing onto the corridor, all ominously empty.

Shepard noted surveillance devices, and disabled them with his Omni tool, but was well aware that it was likely that their presence had already been noted by the time that he began to notice signs that they were under observation.

The next development after the holding cells was the addition of signs of combat; scorch marks, bloodstains, and bullet marks in the walls.

What was far more disturbing, however, was when the holding cells ceased to be empty.

They had found the vast majority of the population of the area.

The batarians didn't seem to have been overly selective in their choice of test subjects, all species were present, mostly civilians, with a few that appeared to have once been mercenaries and pirates.

They all seemed to have been affected by the same affliction as the batarian soldiers, gibbering, some of them bearing injuries that appeared to be self-inflicted.

However, by far the most disturbing sights were the batarians that were present in the cells. They were the most mutilated, often bearing hideous growths and defects that ordinarily Shepard would have assumed had been present from birth. Shepard knew better, here. These were the first test subjects, the rejects, the ones that hadn't been fit for active duty.

All of them responded to the presence of the human marines in one of two ways; the first half shied away, pitifully cowering in the corners of their cells, sometimes gnawing anxiously on their own flesh, whimpering and occasionally snarling at the intruders.

That was the better of the two reactions.

The other half went entirely berserk, throwing themselves at the transparent walls of their cells, completely ignoring the existence of the solid that blocked their path, attempting to lash out at the men, often striking with such force that they damaged their own corrupted flesh, leaving grotesque streaks of blood, pus and general gore on the walls, interspersed with, most sickeningly, gobbets of their own flesh.

This reaction was, unfortunately, the more common of the two.

Shepard was thankful for the walls of their cells, disgusting as the sight of the results of their mindless aggression were.

He was grateful for their existence. Right up until the moment that it became apparent that they weren't fixed. In unison, the doors retracted, and within the space of a second, the two marines were fighting for their lives.