The few hours of sleep Sherlock got that night were spent in a feverish delirium on the couch, where he tossed and turned and sweated through his thin shirt and trousers into the upholstery. The image of John haunted him - at times the doctor took him by the hand and led him somewhere, other times he wiped the sweat off Sherlock's brow with his cool hand, but mostly it was just the thought of John that kept Sherlock bothered, just the mere suggestion of his presence.
Sherlock decided it was enough by five in the morning, so he proceeded to shower and change his clothing, and the cool touch of the brilliant white of his shirt seemed to soothe his mind and give it some structure. By the time he put on his suit jacket he was already thinking of the experiment he had been waiting to conduct, and the preparation of chemical equipment gave him a nice routine to follow; John's appearance in his life also meant that he could get his hands on some medical tools that John sometimes nicked from supply closets, which was a nice addition to his own collection. Sherlock picked up the scalpel he was particularly fond of - it was a little small for his large hands, but, as proud as he was of his pedantic manner of approaching scientific research, he was not a surgeon, and a little imperfection was not at all catastrophic.
Thus he was able to focus on his experiment without the thoughts of John invading his consciousness. His concentration flagged only when his flatmate stirred upstairs at 8:23 am and Sherlock heard the unmistakable creak of the floorboard next to John's bed. It was Saturday, Sherlock remembered, and John would be probably having a lazy shower and then wandering downstairs to have a lengthy breakfast, and then, perhaps, if there were no cases (there were not, at the moment), he would humm and think very carefully about phoning Kelly, which of course would lead to him phoning Kelly, and then John would probably leave with a small smile on his lips and the perfunctory "Might be late, don't wait up." All this, Sherlock's mind supplied, would delay his own exploration of John's strange relationship with pain for at least a day.
"Morning," John said cheerfully, jerking Sherlock from his thoughts to the present, "Jesus, Sherlock, did you sleep at all, or did you spend the whole night doing experiments? When did you start?"
"Just after five," Sherlock answered, turning off his bunsen burner and remaining perfectly still.
"Right, did not think to make some breakfast, hmm? I am starving, I should have never skipped dinner last night."
"You seemed to be in a great hurry to get to your room," Sherlock supplied, watching two crimson spots appear on John's cheeks.
"Yes well, I was knackered, wasn't I - a full day at the surgery, then we spent the whole of evening chasing that bloke...Anyway, I am thinking beans on toast."
Sherlock remained silent, pretending to be concentrating on his experiment, until John looked at him furtively and seemed to be relieved that his flatmate dropped the subject.
"That smell always reminds me of my years at the uni," John said, heating up the beans and smiling to himself. Sherlock watched him carefully - John at the university, that was a curious image, and probably one worth exploring. Sherlock could almost imagine the way his flatmate looked when he first held a scalpel with the intention of dissecting a cadaver; the image made Sherlock reach out and touch his own scalpel with the tips of his fingers.
"Lovely," John murmured to himself, depositing the beans on the buttered toast. Sherlock noticed that there were two plates, and a feeling of warmth filled his chest.
"Maybe this breakfast is a little redundant," John continued louder, "I was thinking maybe I should call up Kelly, apologize for yesterday, and see if she would be up for an early lunch."
"John, I'd like to take a vial of your blood," Sherlock said, deadpan, as John deposited both plates on the table.
"I assume this is for some kind of experiment," John said, pushing the second plate toward Sherlock.
"Correct. Lestrade mentioned a cold case, unfortunately the crime scene is no longer available, there are only black and white photographs of it. I would like to get some of the similar carpeting and stain it with your blood."
"Right, well, this is not the most outrageous favor, coming from you," John smiled, "I'll draw some blood after breakfast."
"I would like to draw it myself."
"And why is that?"
"Well," Sherlock shrugged mildly, "I'd like to learn the procedure. Might come in handy."
"I am not sure how skilled you are when it comes to handling a syringe," John started carefully, "Although I can…"
"No syringe will be necessary. I am perfectly happy to use the finger stick method."
"And I assume you will be using that," John nodded toward the scalpel in Sherlock's hand.
"Precisely, Dr. Watson."
After breakfast John made Sherlock wear latex gloves, which went counter to Sherlock's plans, but the doctor was adamant about proper medical procedure and Sherlock had no choice but to yield. They sat at the table, and both stared at John's hand while the doctor spoke.
"There is really nothing to it," John said, "I usually tell my patients to massage their fingers a little bit, so that there is more blood. If they are nervous I hide the lancet in my palm, distract them, and prick them quickly while they are not looking. I think it's more painful to actually collect the blood, due to all that...squeezing."
"I am certain we won't need any distractions," Sherlock said with a smirk and John giggled, "May I proceed?"
"Of course, be my guest," John smiled at him reassuringly.
The doctor's hand was warm - Sherlock felt it through his glove - and his finger looked inflamed against the otherwise pale skin of his palm. Sherlock carefully positioned the scalpel and, with another look at John's face, quickly pricked his skin and watched John as a small droplet of blood formed on the tip of his finger.
"Well, now grab that capillary tube and start collecting," John said, "If the flow is weak you can stroke the finger from bottom to top, that usually does the trick."
Collecting a vial of John's blood was not a challenge, however Sherlock did not see anything that might have suggested the doctor's pleasure at the slight pain he was experiencing. If anything, John looked mildly bored as he stole furtive glances at his wrist watch. When they were done, John jokingly gave Sherlock a high mark in blood drawing and made the dreaded call to Kelly; they were to meet in an hour, and John adjourned upstairs for some grooming.
Perhaps the pain was too mild, Sherlock thought as he cleaned up and stored the vial of John's blood in the refrigerator. Children might cry during the procedure, but John had a higher tolerance for pain; something more drastic was needed, and as John prepared himself for his date, Sherlock grew nervous and exasperated. He considered coming out with it - just barricading the door and forcing John to sit and listen to him while he tried various things, but that would be...counterproductive. He was disinfecting the scalpel when the doctor came downstairs and peeked into the kitchen.
"Cleaning up after an experiment? Sherlock, you are not yourself today," John smiled as his eyes fell on the way Sherlock was holding the scalpel, "This is too small for you, but I bet if you tried holding it like this…"
He walked toward Sherlock, and all of the sudden Sherlock's mind went into overdrive: here was John, and in five minutes he would be somewhere else, and it was up to Sherlock to prevent it.
Holding his breath and making sure he would not hurt the doctor too much, Sherlock let the scalpel slip from his fingers slightly before cutting the doctor's extended arm.
