With some effort Sherlock managed to explain.
"I had some of the petri-dishes sent to Barts to have them incubated there – it's not possible to keep an even temperature in other than an incubator. They were due that day and had been delivered by an errand boy."
"Errand boy," John mused, "What did he look like?" He had a vague feeling that he had to have met the guy, since Sherlock's exposure to the Tabun couldn't have been long before he had got home. Suddenly things shifted into place in John's mind. Sherlock's meticulous description resembled the man that John had had the unpleasant encounter with on his way home from Tesco's.
"Errand boy! So, that git did tackle me deliberately!"
"What are you talking about?" Sherlock requested, his voice, despite its hoarseness, sounding even more annoyed. Apparently, he didn't like that he couldn't deduce what John had seen.
John explained the little incident with the spilt milk.
"That was right around the corner of 221b. I did have a feeling that the guy hadn't just accidentally bumped into me. He had to keep me away from you for long enough to make sure that you would be sufficiently exposed to the nerve agent!"
"You deduce…", Sherlock added his acknowledgement.
"Huh?" John was baffled. "Er, yes. Yes, I deduce." He smirked and looked down at his hands. Was that a compliment?
The doctor looked up, amazed by the seriousness in Sherlock's voice.
"You haven't told me everything."
"What do you mean?"
John felt his cheeks blush slightly, sensing that they were entering uncomfortable terrain.
"Look at me. If I have been poisoned with Tabun, there will have been reactions in my body to it other than just passing out, as you have told me."
The doctor sighed. Apparently, Sherlock had really been out of his mind by the time John had come back from the shopping. Seemingly, he didn't recall anything about the incident anymore.
"What do you remember?" John asked, examining Sherlock's face for any signs of recollection.
"Hmm…, more or less nothing." Sherlock gave John an intense look. "How serious, John?"
The doctor sighed.
Sherlock nodded slightly and involuntarily groaned due to the pain that the movement caused him.
"You resuscitated me," he stated.
John looked down at his hands again, feeling a little embarrassed. He hadn't intended to tell Sherlock anything about this part.
"How often?" Sherlock interrupted him.
John raised his eyes, now looking right into his flatmate's face.
"How do you know it was more than once?"
"My ribcage hurts like hell, most likely, some ribs are broken. So, either it took very long, which I don't think, going by your current fitness, or you pumped on me like crazy, or… it was more than once."
Oh, Sherlock was already being very Sherlock-like, John thought, somehow relieved and irritated at the same time.
"All three, I reckon," he said, "As to my fitness, … eh, forget it…" John's voice trailed off, he wasn't in the mood and the physical state to argue with his flatmate about his lacking fitness.
The two men looked at each other and burst out laughing, which caused both Sherlock and John flashes of pain. Sherlock was exhausted, groaning slightly and closing his eyes again; John wasn't sure if he himself wouldn't slip off his chair feeling his view narrowed by black margins that clearly hinted on a not so distant faint. He tried to collect himself.
"So, how often?" Sherlock demanded.
"Once all by myself and another one that you definitely wouldn't have survived, if Mycroft's men hadn't arrived just in time."
Sherlock was quiet.
"I can't remember the last bit, though, 'cause I myself had blacked out by then."
"Yes, you got a dose, too. That's why we're both here."
"You deduce...," John stated, causing Sherlock to snort, avoiding another painful laugh.
Despite the effort it took him, Sherlock lifted his hand and stretched it out to John. The doctor hesitated, but took the hand in his own, feeling Sherlock's grip. His flatmate's eyelids opened again and he locked eyes with John.
"Thank you," he whispered, and pressed his friend's hand as firmly as his weak state allowed.
John went all goose-pimply, convinced that for the first time Sherlock genuinely meant it.
"Anytime, Sherlock, anytime."
The last twenty-four hours, as horrible as they had been, had revealed something that John wouldn't have expected to happen in his entire life: The Holmes brothers had verbally expressed an emotion John would never have imagined them capable of – gratefulness.