Sherlock had wrapped up the case at New Scotland Yard within minutes, deducing the life out of the suspect and providing irrefutable evidence of his guilt.
As they returned home to Baker Street, John headed straight to his room to prepare for his date.
John has a date, Sherlock ran over and over in his head.
It riled him how much he was affected by this fact. He'd been fine this morning. Calmer; his emotions tempered; in control.
It was like yesterday's escape from reality had given him a wake up call and everything would be okay - until John dropped the bombshell.
John has a date with Sarah.
The thought crashed through his head, worming its way into ever corner of his brain until he could think of nothing else.
The shower clicked on in the bathroom and disturbed his concentration. Sherlock frowned. Why was he so easily distracted? How did John Watson have the power to distract him?
He needed his Mind Palace.
John emerged from his room some time later, all clean, shaved and dressed for his date.
"Right, Sherlock." he started, pulling his coat from the rack, "I don't know what time I'll be back. I might not be back tonight at all." He gave a suggestive wink to Sherlock who barely noticed him speaking, let alone anything else. He was laid out on the worn sofa, fingers steepled beneath his chin, not asleep - aware but deliberately paying little attention.
"Don't wait up!" John shouted, and he turned and exited the flat.
As soon as he heard the outside door of 221B close, Sherlock shot up from the sofa. He began pacing across the living floor. Window to door to window to door. Muttering to himself. He needed to control himself; control this; he was losing himself.
He stopped pacing and chewed his bottom lip thoughtfully.
It had worked once...
Fifteen minutes later, Sherlock was once more sat on the sofa. The curtains were pulled closed; the small coffee table was cleared, red velvet was smoothed over it; ornate black and ivory box and antique silver candle holder in their places.
Sherlock lit the rich purple candle, watching the flame dance. It was beautiful; hypnotic almost.
In a few short moments, Sherlock closed his eyes as the drug began to flow through his system. He had created a slightly more potent mixture this time, hoping for a longer-lasting effect, and the result was a much quicker hit.
He groaned with pleasure as his mind cleared of all thoughts of anxiety, frustration and John.
A second later - or maybe minutes or an hour, who knew? - Sherlock's eyes flew open. His lungs felt full; tight; restricted, and his heart felt erratic and racing.
The groan that Sherlock emitted at this time was anything but pleasurable.
"Sherlock!" Greg shouted as he mounted the stairs of Baker Street. John had mentioned that he himself wouldn't be in this evening, but Greg needed to get clarification of something Sherlock had said before he could wrap up this basement murder case.
He pushed open the door to 221B and frowned as his eyes had to adjust to the dim lighting. He noticed a candle flicker on the coffee table, almost burnt out, and reached to flick on the lights.
Nothing prepared Greg for what he saw next.
Without thinking twice, he reached for his phone.
"Mycroft Holmes", a voice announced from the other end.
"Mycroft", Greg began. Must calm down, he thought to himself. His heart was pounding in his chest. Sherlock looked... lifeless.
"Mycroft, you'd better get over here to Baker Street. And send some medical staff urgently." he added, almost as an afterthought, knowing that Mycroft would need to see Sherlock, but Sherlock also would need medical help.
"Gregory?" Mycroft enquired, confused by the instruction. He hadn't needed to respond to any sort of Sherlock emergencies for quite some time. Gregory Lestrade had played no small part in ensuring Sherlock's previous recovery from addiction, and the drill had become unfamiliar to the elder Holmes.
"It's Sherlock." Greg clarified. "I don't know what he's taken but he's..." he trailed off, unable to finish. God, he looked so... pale.
"We'll be there very shortly, Gregory." Mycroft informed him, "Please stay with him." A soft click indicated he was gone.
There was nothing Greg could do now except wait. He didn't want to call John. Sherlock wouldn't want that, and Greg wasn't sure whether Mycroft would want Sherlock's drug problem - whether past or present - exposed to the doctor.
Gregory did the only thing he could do. He slid himself underneath Sherlock's head on the sofa and cradled it in his arms until help could arrive.