So, this is a BELATED Birthday prompt for my dear HanHan84, who gives some of the most delightful story ideas, including this gem:

Molly swaps bodies with john for about 12 hours (no - one knows why, all the two remember before it happened was Sherlock leaving the lab to see Lestrade and on his way out, knocking over a flask of something on the bench. They remembered blackness and woke up as they are now ((body swapped))!) They don't tell Sherlock about it but this is how John discovers their secret relationship.

Teeheehee...I do apologize that it's taken me so long to get this done, my dear, but I hope the contents more than make up for it! Love you, and I hope you had a fantastic birthday!

I hope the rest of you enjoy it as well! Thank you!

Disclaimer and all: I don't own anything. None of what I do here is for profit. It's a gift for a friend, and I'm just borrowing characters. Also, please don't steal other people's works. Thanks!

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John sat by idly, watching Molly and Sherlock tag team over the span of the work stations of the lab. He had to admit, even with his experience, both in medical school and the field itself, he would never be as flawless working with Sherlock as Molly Hooper was. He had wondered what changed between the pathologist and detective since Sherlock's near exile. The two had become amiable, Sherlock suddenly making it a point not to spout out his deductions about Molly. She, in return, granted him more access to equipment and corpses than ever before.

A chirp of someone's phone interrupted the veteran's thoughts.

"Yes! Wonderful news! I'll be there right away! Do tell Anderson not to touch anything!" Sherlock pressed his thumb to the screen of his mobile, and pocketed it as he made his way to the door. John stood to join him.

"No, I need you here. Shouldn't be more than ten minutes. John, text me the minute the results of that test are complete. Molly..." John's head snapped to the small woman across the room, spying a shy grin on her face.

"Yes?"

"...Lovely as always." Sherlock was through the door before John could return his widened gaze to him. He missed the way Molly's smile brightened up at Sherlock's words, and he definitely missed the sly wink that the detective gave her in return.

Most importantly perhaps, both of the occupants of the lab missed the shatter-proof flask at the end of the counter falling to the floor. Its mysterious contents slowly dripped onto the floor, while the equally puzzling vapor curled up and lightly sizzled the air molecules overhead.

John had gone back to flipping through a stray copy of the textbook of airborne pathogens, when he heard Molly's the first of Molly's wracking coughs. He was up in an instant, at her side as she hunched over, trying to purchase air in her lungs.

"Molly? What's wrong? Did you inhale something? Come on, stay with me." He could see she was beginning to panic, unable to catch a single breath while her body tried fighting off some foreign intruder. John had stood to rush and get her some water, when a dizzy spell overwhelmed him, sending him immediately onto his backside, eyes flying to a terrified looking pathologist, before darkness took over. The sound of her coughing attacks ebbed into a thick fog, and John felt like he was falling into some of the best and deepest sleep he'd had since being home from the war.

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"...ly ... Mol... Molly, come on. Wake up! Molly!?" John opened his eyes as the voice grew stronger, until he was met with the sight of a frantic Sherlock Holmes looming him. He'd half expected a quick slap on the back, or perhaps a shaking of his shoulders, the detective scolding him and telling him to get a grip. Instead, he received a relieved sigh, while strong hands cradled his head. John was about to ask what had gotten into his friend, the bout of sentiment being the rather obvious clue that he wasn't himself. However, as he caught sight of himself lying on the floor just meters away, John's mind quickly halted any conversation he was about to have.

"Are you alright? Don't worry about John, he can handle himself quite well. My main concern is you, Molly," Sherlock gazed over Molly's face, and John stared back at him, deciding that a nod was his best option for reply. Sherlock gave a reaffirming nod, before helping his friend to stand, before making his way to John's body.

'Oh boy,' John thought as he watched the man trying to rouse him, hoping that Molly would be as quick on her feet in noticing that something was definitely amiss. Namely, them. As Sherlock shook John's body ('Of course, he'd go for shaking'), a small whimper rose from his vocal cords.

"Sh-erlock?" John could see Molly's softness reflected in his own eyes, the tired confusion raising the slight wrinkling lines of his forehead. Sherlock was helping him to stand, making sure his, or Molly's, balance was alright. In the meantime, Molly was still trying to manage her body (his) to stand, finding the new weight and difference to be a challenge. After a brief scare of watching his own frame tumble back to the floor, he called out to catch her attention.

"Mo... John! Are you alright?" He asked, hearing his voice come out in the soft tone of the pathologist's. John knew right away that she had heard her own voice, and her head darted up to meet his gaze. She squeaked in surprise, producing a rather odd tone from the army doctor's vocal cords. Sherlock looked over to her, his left brow raising ever so slightly.

"John, will you please hurry up and grab the first aid kit? Molly has a cut on her forehead. It needs tending to immediately. Then we can figure out what went wrong in here while I was away." Sherlock shooed the doctor away, and Molly, still confused and staring at herself from across the room, slowly made her way toward the cupboard that held the supplies. John was hoping she would be back soon, so they could begin discussing what happened. However, his thoughts were abandoned, as he felt the consulting detective's lip brush over his (no...Molly's) forehead. He gasped, looking up at Sherlock's concerned features.

"I know...I'm sorry. I just needed to. I'm glad you aren't too much worse for wear. Now, let me see that cut." John looked on as Sherlock examined the slice that had gone over Molly's left eye. It wasn't deep, but by the way Sherlock inspected it, one would suspect it had been a fatal blow to the head. John looked back to his own figure, now approaching with the small kit of gauze and bandages. He caught a sort of bashful glance in his own eyes, and began his pondering on the whole ordeal.

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So, I've decided that instead of doing a one shot of this...I'm going to spread it out over a couple of chapters. :) I hope that's okay with everyone. Anyway, here's the first chapter! YAY! Thanks again for reading, and I hope you'll leave a review to tell me how I'm doing.

Happy BELATED Birthday, to darling HanHan84...I hope I'm doing your idea justice.