Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.

Summary: After Sherlock reads an article on the benefits of kissing, he convinces John to take place in a few snogging sessions. . . for science! Lots of medical lingo. There will be six parts in all.

Warnings: None, thus far.

Word Count (this part): 1,237

A/N: Any medical lingo you don't recognize should be at the bottom.

4 Times Sherlock Kissed John for Science, and 1 Time John Kissed Him

"John, could I ask a favour of you?" Sherlock asked, never taking his eyes off the screen of his laptop.

John glanced up from the newspaper he was reading to look at Sherlock, quirking an eyebrow in interest.

"What could I possibly do as a favour to you, Sherlock?" John asked.

Sherlock looked up from his laptop then, studying John's facial expression to determine whether he was genuinely considering assisting him. After a short moment of examination, Sherlock decided his flatmate was interested enough and let out a long, drawn-out breath.

"To start, I need you to listen through my entire explanation without interrupting me. Can you do that?"

John nodded silently.

"Good," Sherlock responded.

He cleared his throat, closed his laptop and set it aside before continuing.

"Let me give you some background information before I begin." Sherlock cleared his throat once more. "I recently stumbled across an article that listed some benefits of kissing to a person's health. The first one I read mentioned that blood pressure increases while kissing, but an article about the same matter said that a person's blood pressure decreases. These conflicting 'results' on the same experiment debunks one of the articles' credentials, and I must find out which one is correct. Do you understand?"

John, who had dropped his newspaper at the word "kissing," was sitting with his mouth slacked in shock.

"I, uh. . . Wha- . . ." John attempted to stutter out a response. "I mean . . . erm, I understand, but what. . . What do you need me for, exactly?" He cleared his throat awkwardly.

Sherlock attempted to contain a smirk at John's reaction.

"I need to find out which one is correct, obviously. That is where you come in."

John was shaking his head, trying to stop himself from interrupting while also attempting to keep himself seated instead of dashing out of the flat.

"You could use anybody!"

"That is incorrect. The experiment has to be done on someone who is healthy and not at risk, based on family genetics, of having high or low blood pressure. I checked your family's medical history all the way back to your great-grandfather, Eugene. Not a single person on your family tree has had hyper or hypotension, making you the perfect test subject."

John refused to respond for a moment, silently cursing every individual who owed Sherlock a favour. Had they not owed him, Sherlock never would have found out that his family had an immaculate medical history: no heart attacks, no strokes, no hypertension, no genetic disorders. . . Nothing. His sister's alcoholism was the closest thing to a mental disorder in his entire family.

John knew there was no way to get out of this, now. When Sherlock was adamant about something, there was no dissuading him.

"Fine," John finally responded, disdain evident in his voice. "I'll do it."

Sherlock jumped up from his chair and ran into the kitchen. John heard some test-tubes clanking together, a glass something shatter and a worrisome-sounding thud within the first few seconds. He was too annoyed to care, though. The doctor dropped his face into his hands, trying to will away this entire situation.

After a few more minutes of listening to Sherlock toss things about, John heard hurried footsteps coming from the kitchen directly toward him. He lifted his face from his hands and looked up to see his flatmate standing in front of him with a sphygmomanometer in his hands and a stethoscope around his neck.

"Roll up your sleeve, John," Sherlock demanded, bending down on one knee next to John's armchair. "I know you've done this on thousands of patients, so I shouldn't have to tell you to relax."

John rolled up his sleeve until the fabric was bunched up at his shoulder. Sherlock immediately started snaking the cuff up John's arm until it reached his bicep, where he tightened it until it was snug, and fastened the Velcro parts together to keep it in place.

Sherlock leaned back to his normal kneeling position, placed the eartips of the stethoscope into his ears and began squeezing the bulb to inflate the cuff. When it was just tight enough, Sherlock stopped inflating it and placed the bell of the stethoscope on the crook of John's elbow. He began decreasing the pressure of the cuff slowly, and carefully watched the monitor while listening for John's heartbeat to determine John's systolic and diastolic pressure.

John let out a slow breath as Sherlock completely deflated the cuff and removed it from his arm. Sherlock ran over to his laptop, opened it, and typed the result into a Word document that was completely dedicated to this experiment.

Shortly after, Sherlock set aside his laptop once more and made his way back over to John.

"Perfect blood pressure for your age. Congratulations. Now, are you ready for the independent variable?"

John sighed but nodded nonetheless.

"Stand up. We're going to move to the couch, since I'm assuming you probably don't want me sitting on your lap with your psychosomatic pain and all that."

The doctor stood up, walked stiffly over to the couch and sat down. Sherlock followed suit, sitting directly next to his flatmate with his body turned slightly toward him. John just stared directly in front of himself at nothing, avoiding eye contact with Sherlock.

"You need to relax," Sherlock said, dangerously close to John's ear. "My result will be off if you don't calm down. Just close your eyes and pretend I'm some woman you have taken back to your flat after a nice date."

John closed his eyes as he felt cold fingers turn his face gently to his right. He felt surprisingly soft lips graze his and shuddered.

'I can't believe I'm letting him do this,' John thought as he felt the lips touch his again, a bit harder this time.

Sherlock began legitimately kissing John, cupping his face with his right hand and applying a bit more pressure than he had on the first kiss.

John began returning the kiss after a few seconds of hesitation. He rotated his body slightly in order to make the connection a little less difficult and started trying to gain some control in the situation. If he was going to be an experiment, he may as well perform to his full potential, he figured. Plus, his flatmate's lips were incredibly soft, and he was also quite. . . skilled with his tongue.

After a few minutes (3 minutes and 27 seconds, to be exact), Sherlock ended the kiss. By the time John had fully opened his eyes, Sherlock was across the room, grabbing the blood pressure apparatus and stethoscope.

"Now, let's take a look at the result, shall we?" Sherlock asked as he made his way back over to the doctor.

Sphygmomanometer – A device used to measure blood pressure, comprising of an inflatable cuff to restrict blood flow and a mechanical manometer to measure the pressure.
Stethoscope - A medical instrument for listening to the action of someone's heart or breathing.
Systolic pressure – The blood pressure when the heart is contracting.
Dystolic pressure - The blood pressure when the heart is relaxed.

Next chapter: Sherlock needs to test the effect kissing has on O2 saturation.