Running after Sherlock, John could barely see him. The moon would occasionally shine through the thick trees, illuminating a bit of blue scarf or lighting up a bit of his face, but mostly John was following disoriented beams of flashlight and the rustle of leaves. It was terrifying; all he could do was keep up and pray to hear no bullets. _If he's to go first he should take the gun, why does he never take the gun_ Finally he came to stand next to Sherlock, and saw Henry, extremely unstable. Sherlock was talking him down, with surprising success for a self-proclaimed sociopath, but John was having a hard time seeing past the gun.
Every bit of John was alert and on edge, which usually provided him with the delicious aliveness he so often craved. But this night was different. Fog nearly enveloped Henry and advanced menacingly towards where Sherlock stood. John felt exactly as he had once in Afghanistan, his unit had gotten pinned down by the enemy and had sustained extensive damage. What's more they were not strategically located, and it took 2 and a half days to get backup. Nobody except the injured got any sort of sleep, least of all John. He was constantly in a flurry checking up on one injured soldier to the next, making sure they were breathing, calling time of death when they were not. A field kit was useful, but it was no substitute for a field hospital, and the truth was trapped as they were John was unable to administer the care that would have otherwise given them a chance. A lot of John's friends died those days, slowly in great pain, and John remembered their screams. All the while the enemy kept relentless watch and never missed an opportunity to fire. There wasn't anything about that ordeal that was the least bit appealing. John had felt pinned. He had felt as if a great beast was stalking him and those he was charged to protect, and there was no hope of outrunning it. Eventually the beast would leap and then it would be simple: John would die or he would kill. The apprehension, fear, and paranoia he felt during that time was overwhelming, John kept it together because others were falling apart, but his sanity was bound by the very last ropes of his adrenaline, strengthened some by his will to endure, but steadily being frayed by exhaustion and the sound of his men in agony.
A bit not good.
John couldn't say why he felt this way now; this was hardly the most harrowing situation he'd gotten into with Sherlock, and he wasn't particularly exhausted, he'd eaten in the last 12 hours and he'd gotten 4 hours of sleep, which when things got hectic on a case was pretty good.
But he did, he felt almost ready to break.
Sherlock had said something wrong. John's inner "worry for Sherlock" scale went down a few notches, as Henry had stopped pointing the gun at him, but his inner "worry for patients" scale skyrocketed, as now Henry had it in his mouth. John inhaled sharply, breathing in the misty fog which now wafted around him. _The beast is leaping, the beast is leaping_ his mind screamed, but there wasn't a whole lot John could do to kill this introspective beast. John kept his voice level and calm, trying to talk Henry down, and he took a few steps forward, trying to increase the chances that if Henry's current state bore any fallout, it would reign down on him, not Sherlock.
Sherlock knew how to remedy his mistake however, "Henry remember. "Liberty In." Two words a frightened little boy saw here twenty years ago." Henry was listening now, but Sherlock would have to tread very carefully. "You'd started to piece things together, remember what really happened here that night. It wasn't an animal, was it, Henry?" Even at such a time as this, John mentally told himself to commend Sherlock on his bedside manner. His tone was perfectly calm and soothely, his posture nonthreatening and open. "Not a monster. A man."
Henry seemed stricken, and the gun fell to his side. The fog had cleared a bit where Henry was and it looked like he was remembering something important. In the background John heard Lestrade coming down into the hollow. "You couldn't cope. You were just a child, so you rationalized it into something very different. But then you started to remember, so you had to be stopped: driven out of your mind so that no-one would believe a word that you had said."
John figured that this was a good time to try and disarm Henry, so he softly advanced, and took the gun. Henry's fingers were limp and he gave John no trouble. John knew that the worst was over. _Sherlock killed the beast_ John thought with a swell of admiration and respect. Henry mumbled, "But we saw it: the hound, last night. We s… we, we, we did, we saw…"
All knowing, Sherlock said, "Yeah but there was a dog, Henry, leaving footprints, scaring witnesses, but it was nothing more than an ordinary dog. We both saw it- saw it as our drugged minds wanted us to see it. Fear and stimulus; that's how it works. But there was never any monster.
The words which had sounded so wise and comforting to all in the hollow a second ago seemed hideously wrong, when a shadow moved through the fog and growled. John's fearfulness was astronomical, any higher and he would lose his mind completely. As he was his hands had never been stiller, not even during the war. The beast was prowling and it was a beast, no dog. It's eyes were the color of burning bodies, and his teeth were as white as the sinister lab John had been trapped in. John took a moment to assess the situation. Henry was in a full blown panic attack and Sherlock seemed more considered about that then the spector of death currently coming closer. _Drugged! He thought furiously. You were drugged remember?_ Except, no. Lestrade. Lestrade wasn't drugged and he looked frozen in terror. In a desperate quest of clarity John shined his flashlight at Lestrade.
"Greg, are you seeing this?" John asked but he didn't answer and he didn't need to. "Right: he is not drugged Sherlock, so what's that? What is it?"
Sherlock was unraveling just as fast as the rest of them, but he managed to give a shaky answer. "All right! It's still here… but it's just a dog Henry! It's nothing more than an ordinary dog!"
In response the beast howled, and it sounded like bullets and screams. Every ounce of John was focused on standing upright. Out of the corner of his eye John saw Sherlock grappling and shouting unintelligibly with some shrouded demon that looked a little like John's father when he'd had too much to drink. The last pillar of sanity in his brain, told him that he was going to have to fight, and if he was going to have to fight he was going to have to see who he was fighting first. So John squinted and he saw Dr. Franklin. Apparently so did Sherlock, who was manically voicing his ongoing realizations. "The fog. It's the fog! The drug: it's in the fog! Aerosol dispersal- that's what I said in those records. Project HOUND- it's the fog! A chemical minefield!"
Greg covered his mouth but John didn't bother. There was no getting away from it now. He couldn't see distinct images anymore. Just dark figures.
"Kill it! For God's sake somebody kill it!" Franklin shouted, and it was the first useful thing anyone had said since all the insanity began. Lestrade fired, but his shots were erratic and he missed. The Hound leaped, and John took a millisecond to absorb his utter terror, and John answered it with a raised gun, tensely aware that if he missed there would be no second chance. The beast would kill him or the fog would.
John didn't miss. The dog fell, and when it stirred again shortly John didn't miss either. Anyone who was looking at John's face would never have imagined the panic he was experiencing inside. John had killed many beasts.
There was no way to survive a fog other than go through it and hope to God you didn't get lost along the way.
So far, John never had.