A/N Set between episode 21 and episode 22.

Metronome

Sherlock had never really had anyone in his life that had been a calming influence on him. He had torn through the world like a hurricane and people had dived out of his way to avoid the destruction. Lestrade hadn't run, opting instead to try and get closer. Lestrade had been left broken in the dust.

When he met Irene Sherlock realised that he hadn't really known what out of control was. Irene had held his hand as they jumped off the cliff together, tumbling in glorious roaring and wind as life tore by, until she'd opened her parachute, jerking from his grasp to leave him hurtling to the sharp rocks below. Out of control. Those rocks had been sharp indeed. They left gashes inside him that no one could see. Now Sherlock was the one broken in the dust.

Then, one day, the father who had never really cared, never really noticed, decided to perform a selfish yet life saving act. He hired a metronome by the name of Joan Watson.

Watson was his balance. She stood by his side gently ticking away, providing him with rhythm. He was a whirlwind around her steadiness. At the centre of his storm was her calm. He would tear towards the edge of the cliff, but she stopped him tumbling over. Watson was the exact opposite of Irene. No matter how off time he became she was a constant beside him, ready for him to fall back on the steady, gentle rhythm. His constant. His metronome.

There were times more and more recently when Sherlock had wished that he had never taken that nostalgic trip back to London. It had brought him nothing but trouble, both in the persons of Lystrade and then Mycroft. He wished Joan had never met Mycroft. When that man, who he had the misfortune to share a father with, was around, Joan would drop a beat. He would feel himself fall into the pattern with her only to stagger as if she were one second behind. The sensation would hit him, like putting his foot out in the dark to hit the final step that wasn't really there; that sudden sickening jolt that accompanied the reality.

Sherlock had been becoming accustomed to mimicking her rhythm, her balance, but then Alistair died and he felt the knock hit him out of time. Suddenly he was a whirlwind again and when he came to he was sat in a van, covered in white powder, thinking that his time had finally run out. His beat was wrong. He staggered and tried to right himself but he couldn't catch up, couldn't keep the beat. He turned and waited for the guiding tick, but she wasn't there. She was out having dinner somewhere with Mycroft. Suddenly his hand was holding a small packet of Cocaine but instead of throwing it away he watched as it slipped quietly into the folds of a book.

He needed her back. He needed her to know what he had done. He needed her to see what he was hiding like she had every other time he'd tried to jump. Yet the silence deafened from every direction and he realised he was sat alone in the dark with the wind slowly building and the edge of the cliff gliding softly closer.

"Watson," he called out into the dark, but a slammed door echoed back.

He reached out his hand and felt his fingers brush the edge of the cliff, crumbling down to the rocks below.

He'd told Mycroft what would happen. He'd warned him. Again and again he dialed her number, trying to quieten the wind with only her voice asking him to leave a message.

A shrill screech pierced the dark and he opened the front door as the edge of his world faded between the Brownstone and the darkness.

"We need to talk." Mycroft spoke with his lips but Sherlock heard the confession a second before from his eyes. "It's Joan."

He heard a sharp crack as the metronome splintered, as his mind splintered, and the wind came roaring out, engulfing everything in its path.

"What did you do?"

Mycroft stood in the doorway, facing the storm that was his little brother, and realising slowly that he hadn't seen Sherlock like this for a very long time, realising slowly just what Joan was to him.

He almost pitied whichever man chose to stand in the way of the whirlwind.

Someone was going to be left broken in the dust again. Mycroft just had to ensure that it wouldn't be Sherlock.