A/N Suddenly realised this was still sitting on my hard drive from... well, ages ago. That is, I think, a crime, so, Johnlock if you like it, or just really close friendship if you don't! :)
The dark days were the ones John feared the most. The empty stares; the silences; the sheer apathy of his flatmate was almost more than he could bear. They let him know that the walls had gone up and all he could do was wait for them to come tumbling down again. He longed for that moment, when the dam would burst and 221b Baker Street would be flooded with tears, tantrums and an ocean of self-loathing. At least while he was being sobbed into or screamed at he knew the younger man was still alive. More than once during the preludes to these emotional explosions, John had found himself checking on the consulting detectives pulse, just to be certain that he hadn't, in fact, shuffled off this mortal coil.
For Sherlock, the moment his carefully constructed walls shattered like so much fragile glass was the thing he feared the most. When one consistently suppresses one's emotions, one has to expect them to hit in a tidal wave occasionally, but that didn't mean he had to enjoy it. He had coped when he was young, mostly due to Mycroft's intervention. Much as he hated to admit it now, his elder brother had always been there when Sherlock needed him. Until he had left for school that was; after that those moments had become his own personal hell. Sherlock's biggest fear was suddenly that he might drown in the wave of emotion or worse, be swept away by them, never to be found again. Lost in the darkness.
When he'd first met John Watson, he'd been afraid - so very, very afraid - that his new friend (his only friend if he was honest) might abandon him when he saw what a mess his flatmate really was. There, John had done what few could do - truly surprised him. When Sherlock had feared he would flee, John had only stepped in closer and hugged him tight. And somehow that made it all okay.
Yes, Sherlock still feared his emotions, but that fear was no longer so all consuming. Now he didn't have to do everything he could to avoid them, for he knew he'd never be lost to them. Not as long as he had John Watson by his side. John would be his safe port in the storm of his mind. He was a rock to cling to in the dark of his worst moments and, with all his strength, Sherlock clung on.
