Though it had been a while since he was a soldier, John's sleep was still peppered with nightmares from the war. It wasn't like he wasn't around action or violence a lot, but solving crimes with Sherlock was different from war.
During warfare, one wrong step or one unlucky choice could get your limbs blown off— or worse. It was random; in the chaos, some soldiers often threw grenades or fired blindly. You got confused as to who was on your side and were sometimes left to fend for yourself. Adrenaline took priority over reason.
Catching criminals with Sherlock was so much different. It had a bit of order to it, as there was rarely more than a few people. Sherlock was always thinking things through, even in the worst of situations. Adrenaline was rare to cloud his brilliant mind. He always knew when John was or wasn't present on a case, however absent of the fact he might be otherwise. John not only knew who was on his side, but also by his side, both in a figurative and literal sense. As robotic as the man might seem at times, John knew that Sherlock cared. It was the little things that Sherlock did, such as glancing over his shoulder while chasing a criminal to make sure that John was still behind him. Although he would never admit it, on the less intense chases, John would secretly drop behind on purpose so that when his footsteps were out of Sherlock's earshot, he would get to savor that rare caring glance.
The nightmare that John was having offered no such comforts. It was pure chaos. Blood splattered in the air and soaked the ground. Explosions and gunshots bombarded his ears, the sounds vibrating to his very bones and overwhelming his senses. The area reeked of gunpowder and burning things and blood, the smell so thick in the air you could taste it. Yells and commands and unearthly screams echoed around the battlefield. The thick cloud of gunpowder and smoke was only disturbed by the bullets screaming past.
Here, there no person was looking out for him. If he fell now, he wouldn't be noticed; just another corpse on the field. John shuddered and resolved to try to keep that from happening. He clutched his gun and marched forward, eyes forward, trying to disregard the figures falling around him. He only had a second to realize that there was a bullet sailing for him, its metal body adorned with a single bloodthirsty fang. He completely froze, and…
John cried out, sitting up in bed, hand reaching up to cover the spot where the bullet would have hit. He panted, clutching the blanket, trembling and covered in sweat. He shuddered. Despite being tangled in the blanket, he was so cold.
Still shaking, John untangled himself and got up. He tested his strength with a few hesitant steps, then exited his bedroom and went down the hall.
He soon found himself at Sherlock's door, despite not consciously telling himself to go anywhere. He opened the door as quietly as he could and peered inside the room.
Moonlight filtered through the window, gently silhouetting the sleeping figure on the bed. John listened to the gentle snores for a few minutes; a welcome contrast to the noises of the dream.
John mentally pep-talked himself into going back to bed, but he couldn't bring himself to turn around and leave. The peaceful aura of the room sank into his nerves, calming his trembling figure. Yet he was still frigid, not the type you get when you've been outside on a snowy day, the kind that it feels like your blood has been frozen from the inside.
John knew what he wanted. He wanted to just curl up beside his best friend and hold onto him. This was the person who wouldn't desert him. This was the person who wouldn't leave him. And, or so John really hoped, this was the person who loved him.
After some mental debate, John reasoned that the jumpiness would make him a light sleeper tonight and that he could leave before Sherlock even knew he was there. Otherwise, people would talk.
Carefully, as to not disturb his slumbering friend, John lifted the blanket and slipped under it. He was about to get into a comfortable position when he noticed that the snoring had stopped.
Panic shot through him as he saw Sherlock's head rise off of its pillow. Sherlock looked around, then rolled over to face John. Their eyes met for a second.
"John." The word wasn't a question, nor was it spoken in a concerned or angry tone. It was just a warm statement from the voice of a sleep-laden man, not dissimilar to the way a toddler might point out a simple object and declare "cat" or "plane".
Sherlock shifted his pillow so that it was just overlapping John's and pushed himself over. He then enveloped John in his arms, lacing one of his hands' fingers in his hair, snuggled into his pillow, let out a sleepy sigh, and was again asleep.
John blinked twice. What? He shook his head and shrugged, unable to keep a smile from spreading across his face. Alas, Sherlock had proved again that no one would be able to figure him out.
John cuddled Sherlock tightly, wrapping his arms around the detective. He rested his head in the crook of Sherlock's neck and breathed deeply, tracing designs on his back. Sherlock's scent spread warmth through him, chasing the cold away from his every last cell.
Nightmare forgotten, John drifted into a deep sleep.