John woke up in the morning, drenched in cold sweat, his throat slightly hoarse from a scream that had died as he woke up. He closed his eyes for a second and waited for his heartbeat to return to normal after the nightmare he always had. The one which would fade until he next looked at Sherlock when it would bubble to the surface in his mind, turning up like a bad penny. The nightmare which might turn up when he passed St Bart's or that might simply turn up in the middle of the day and then the next night it would begin again.
When his heartbeat and breathing returned to normal he opened his eyes, swung his feet out of bed and padded over to the door. He rested his head against the door before pulling his familiar frayed dressing gown down from the hook and pulling it on laboriously. He opened the door slowly and saw that Sherlock was walking around quietly in the time that he had taken to pull his dressing gown on. He looked down at his slipper clad toes and shuffled over to the kettle. It was either shuffle or limp and he'd rather shuffle. Sherlock watched John for a few minutes before turning to the window. It almost hurt physically to look at him, though he wasn't sure why.
John pulled down his mug before hesitantly saying, "Would you like some tea?" his voice surprisingly steady for addressing the man he had just watched fall from the roof again in his mind, his subconscious grabbing hold of that image like it was a lifeline and strangling him with it.
"No, thank you," Sherlock said quietly. "John..." he started.
"I have to go to work, Sherlock," John said, starting to limp to his room, abandoning the tea still unmade on the surface. "I took a job after..." he elaborated just before he slipped inside.
Sherlock sighed and waited for John to come out dressed (seven minutes later) and watched him leave. He knew as well as John did that he didn't have to leave for another hour but he let him go.
That evening they didn't talk much, John disappearing into his room after claiming he wasn't hungry enough to eat, Sherlock doing the same. That night, and for several after, Sherlock listened to John's nightmares. Every day John avoided Sherlock and after a while Sherlock gave up talking to John.
A fortnight or so later Sherlock was watching the ceiling again. Breathe in, breathe out. Count the heartbeats like beats in a bar. Sherlock closed his eyes and listened. "He's my friend, let me through!" It was the same calling as usual. The one where every word was like a knife stabbed into Sherlock and being twisted before being pulled out slowly. Sherlock opened his eyes and got out of bed quietly. He walked into the flat. The skull had been moved, Sherlock had known that but he hadn't had the courage to look under it so he finally did. And a small smile bit at the corners of his lips. He picked up the note and put it in a pocket in his pyjamas.
He walked to John's door and placed both his palms against it before pushing it open slowly. He walked in, feeling the soft carpet against his feet, closing the door quietly. He hesitated for a moment before walking to the other side of John's bed and slipped in, trying to disturb John as little as possible. He slowly moved closer and wrapped his arms around John as the scream broke through his lips, early compared to some nights and late compared to others. "Sh-Sherlock," John sobbed, gripping Sherlock's pyjama shirt and crying softly into it.
"Shh, I'm right here John," Sherlock said as John gripped him tighter, tangling his legs with Sherlock's a little, gripping onto that lifeline, praying that if he gripped the lifeline hard enough it wouldn't strangle him. Sherlock pressed his lips to the top of John's head softly. John barely registered it, still half in a nightmare, the other half in a nightmare which had a little oasis of peace in it somewhere. He just gripped Sherlock tighter until he fell asleep again, nestled into Sherlock.