A/N: I was finally able to update the cover art to reflect a scene from chapter 11 drawn by Rebka 18 (rebka18 dot tumblr dot com).

Sherlock surveyed the kitchen, trying to see it through Molly's eyes. She had texted last night inquiring if he was available for an experiment today but refused to give any details beyond "you're going to love it." Molly liked a clean and organized work space (for that matter, so did Sherlock; he was just more literal about the space he actually worked in, while Molly extended her definition to the surrounding environment) and had threatened to take her mysterious body part back to the mortuary if she perceived "even the faintest possibility of cross-contamination with foodstuffs in that laboratory you call a kitchen."

Sherlock thought as long as he kept her away from the oven and its collection of dirty dishes, he would be okay. It was highly unlikely anything Molly brought him needed to be baked, whereas most biospecimens required refrigeration for storage. He'd cleared the entire lower shelf in anticipation (after a bacteria broth had overturned onto a box of lo mein and dripped into the vegetable bin, John insisted all biohazards go on the lowest shelf only) and set up his microscope in the center of the table where they each had room to work on either side. Sherlock was still debating whether he should move the scope to the small round table to free the main table for … whatever … when the doorbell rang.

Molly stood on the steps with her coat zipped and her pink-and-black striped scarf wrapped round her neck, holding a styrofoam cooler with bright orange biohazard labels.

"What is it?"

"Hello to you too, Sherlock." But she held out the cooler. "See for yourself."

He took it, climbing the stairs three at a time and prying off the lid as soon as he set the cooler on the kitchen table.

"Ohhh," he breathed.

"Isn't it great?" she called, just now coming into the flat.

Inside the cooler, carefully packed in dry ice, was a hand. A right hand, male by its size, and burned to a crisp—in places. In other places, the skin was white and shiny, with scattered blisters and a few areas of mere redness.

Molly had stopped to hang up her coat and scarf before joining him and now peered round his arm at her specimen. "First, second, and third degree burns all on the same appendage. I thought you'd like to examine the tissue for chemical analysis and cellular damage that might indicate the accelerant and heat of the fire."

"Yes! Yes, I would."

"All right. Let's get to work." Molly pulled the box of safety equipment towards her.

Sherlock accepted a pair of goggles, pushing them back onto his head, and turned to get additional supplies from a cupboard. "How did you manage to smuggle an entire hand out of the mortuary?"

"He donated his body to science," she said cheerfully, pulling on a pair of gloves and selecting a scalpel from the box he held out to her. "I read his chart. Healthy as a horse. I'm sure he didn't plan on dying in a house fire, but his body is much more interesting like this."

"Obviously."

One of the advantages of being six feet tall was the ability to look over other people's heads. Sherlock did so now with Molly, standing behind her as she made the first incision. She leaned forward to grab a mini rake retractor, and her bum pressed against his thigh.

Sherlock felt as if he'd been scorched.

"Oh!" Molly said, turning with an embarrassed smile. "I'm sorry."

"No, I—" He cleared his throat and stepped to the side. "I must have been standing too close."

She returned to her work, carefully excising samples from various regions for him to examine. Sherlock took the chair opposite, only to discover their height difference put him at eye-level with Molly's chest since she remained standing (no drugs in her bra today). He dropped his gaze to the hand itself.

"That looks like a liquid splash pattern," he said, indicating the irregular burn margins on the back of the hand.

"Yes. But from what?"

Something in her voice, just the slightest hint of uncharacteristic smugness, caught his attention.

"You already know the answer, don't you?"

She nodded, her long ponytail swinging with the motion. "I told you, he donated his body to science. He's already been examined by the medical students and the path house officers. I called dibs on the right hand."

So, she'd requested this hand specifically. Why?

"Was it the more burned of the two?"

"No."

"He was left-handed."

A wide smile. "Yes. His dominant hand was extensively burned as he used it to try to free himself. What else can you tell me about him?"

Sherlock accepted the challenge and bent over his samples, intent on finding out everything Molly knew through observation and experimentation.

()()()()

Having collected a sampling of the various types of tissue damage present, Molly began preparing slides for microscopic examination. It really would have been best to have had Sherlock come to the path lab, but she'd been looking for an excuse to come to Baker Street since she'd gone with Sherlock to the CO poisoning more than a month ago. He had been both infuriatingly oblivious and genuinely thoughtful that day, and Molly was dying to find out what he would be like when the two of them were alone together. Oh, he'd been into Barts since then, sometimes for a case and sometimes not, but even if John or Greg wasn't with him, there was always the chance they could be interrupted. Not to mention the more formal, professional atmosphere of a medical lab and mortuary. But today was an ordinary Wednesday morning, John was at the surgery, Sherlock had no pressing cases, and Molly had the day off since she had to work this weekend.

"Sherlock, can you—" A cover slip appeared in her field of vision. "Thanks."

He hovered over her shoulder, standing carefully to the side rather than behind her as he often did when they shared one microscope. If she stuck her elbow out ever-so-slightly, she would brush the fabric of his light blue dress shirt.

"Finished with the gross examination?" she asked.

"Yes."

"All right, take a look."

She passed him the first slide, and his fingers brushed the length of hers as he took it. Sherlock always moved with such deliberateness and precision there was no way that was an accident, much as he may have wanted it to appear so. Molly glanced at his face, but it was turned away from her as he fitted the slide into the clips.

She returned to slide prep, listening to Sherlock's observations and prompting him occasionally. He got bored with the slides quickly and pushed the hand in her direction.

"Dissect it."

Molly looked up in surprise. "You don't want to work with the burned tissue?"

"He was an idiot who poured lighter fluid over the wood in his fireplace and struck a match. I'd rather watch you work."

"How could you possibly know about the lighter fluid from microscopic examination?" she said, skipping over the part where Sherlock liked to watch her.

"I knew that from gross examination and chemical analysis. The splatter pattern, the residue … obvious."

Molly sighed. She had so hoped to challenge him today.

"The hand itself is interesting," Sherlock said quickly. "But he was an imbecile."

"Okay, well—" Molly brushed aside a stray piece of hair with her forearm, careful to keep her dirty gloves away from her face. "What do you want to do with the hand?"

"Can we look at the muscle? Compare it to the slides you brought right after I came home?"

"Disease versus trauma. Okay." Molly picked up the goggles Sherlock had laid aside when he sat down at the microscope and handed them back to him.

Sherlock moved the microscope out of the way, and she worked in silence for a few minutes, he having spent enough time with her in the mortuary to anticipate the different instruments she would need next and hand them to her. Molly was trying to expose the ulnar nerve, holding the muscle out of the way so she could see what she was doing, but without being attached to an arm, the hand was sliding all over the cutting board with every movement.

"Here," he said. But instead of simply reaching out to steady the specimen, he grasped the retractor with his left hand and placed his right arm around her to hold the hand in place. "Is that better?"

Molly shivered as his voice rumbled near her ear. He was, in effect, holding her, even if they weren't touching.

"Yes, that's—" A slow, deep breath. "Thank you, Sherlock."

Now free to use both hands for precision work, Molly made rapid progress, describing the structures as she went.

"Here's the insertion of the flexor pollicus longus muscle, which flexes the distal thumb joint," she said, leaning to one side so Sherlock could easily see over her shoulder. "We can't see the body of the muscle because it's located in the forearm. It's unique to humans."

Sherlock made a noise of interest and leaned forward. His face was very, very close, and Molly held very, very still.

"You can see the burn damage on the muscle here," he said, indicating the medial side of the hand.

"Yes, that's a deep tissue thickness burn."

"May I try?" Sherlock sat up, his right arm brushing her back as he withdrew it.

"Yes," Molly said, dropping the scalpel and forceps and pushing back from the table, relieved to put some distance between them.

"Where are you going?" he asked, looking up.

"I just—these goggles are bothering me," she fibbed, pulling them away from her face and rubbing the bridge of her nose.

Sherlock returned to the hand, extending her incisions. "Molly, what's this?"

"Hmm?" She bent forward, trying to see what he was referring to in the second finger, and their goggles bumped. She giggled and turned the half-inch to see him. "Sorry!"

But Sherlock wasn't smiling. He stared at her with the focused look of concentration he wore when working a problem. Molly had imagined what it would be like to be the object of the same scrutiny he gave to his work, but she had underestimated the intensity of the experience. She felt pinned, immobile, held in place by what she saw in his eyes. He was close enough she could see the faint beginnings of shadow along his jaw and the curve of individual lashes. Without thinking about it, she ran her tongue over suddenly dry lips.

His pupils dilated.

Molly stopped breathing. They hung like that a moment, staring into each other's eyes through scratched polycarbonate, Sherlock's hands still holding a scalpel and a burnt appendage and Molly's hands flat on the table. She didn't dare close the distance between them, didn't want to be the one to move first, to break the spell. His eyes danced all over her face, and she could almost see him processing actions and reactions before he looked away and cleared his throat.

"Right here." He tapped the area he meant with the flat of the blade. "What's that?"

Molly took comfort in the slight tremble of the scalpel in Sherlock's hands even as she took a quiet breath to steady her own nerves.

"I, um, I'm in my own shadow. Hang on a second." She walked round the end of the table, leaning forward from the other side. "Let me see." She held out her hand and he turned the scalpel, slapping it neatly into her grip. "It's a fracture, I think—yeah. The proximal phalanx."

"In the fire?" He was shooting her little glances now, looking away before she could catch his eye.

Molly smiled to reassure him but didn't look up, giving him the space he needed. "No, this has already healed." She handed the knife back to him and made a show of stretching her back. "So, tell me about the lighter fluid. What did you test it with?"

Sherlock latched onto the distraction at once, pulling over the chemicals he'd used and explaining his process. The awkwardness between them passed, and once they had demolished the hand to Sherlock's satisfaction, Molly let him show off for her by imploding an aluminum can (A-level chemistry, but a cool trick nonetheless). By the time she left Baker Street some time later with a cooler of mangled hand parts and a bag of chemical waste to dispose of at Barts, they had returned to their usual familiar ease. Molly didn't know exactly what had happened when their goggles bumped, but she knew this:

It hadn't been her imagination.

()()()()

"Well?" Molly said anxiously.

It was ten days before Christmas, and Molly had returned from what had become a weekly dinner with Mary to find Sherlock in her flat, ready to share his opinion of the third draft of the paper she was planning to submit to the Journal of Clinical Pathology.

"Your conclusion is too wordy," he said. "The results of your research were unambiguous, and the implications are clear. You're dancing around the issue—just say you've found a better way to do it. The rest of the paper backs you up."

"Okay." Molly handed him a pen from her desk, and he marked out several sentences.

"And here—" He flipped back several pages. "I didn't understand what you meant by this. Is it because I don't have the necessary background knowledge, or do you need to explain it better?"

Molly placed a hand on his shoulder and leaned in to read where he indicated. "I think it's clear, but I'll get John to read it just in case. Anything else? Typos or anything?"

"None that I noticed, but I didn't review your bibliography."

"Would you, please? As many as I've done over the years, I still have a hard time proofreading them." Commas and full stops and colons; Molly had a hard time keeping straight what went where, which titles belonged in quotes and which in italics, especially when she was doing a whole list of citations.

He nodded. "I think you need another chart of your results here," he said, tapping a long paragraph full of technical information. "It would be much easier to see the correlations if the data were presented visually."

"I thought of that, but I'm worried it will make the layout too difficult if I add another chart."

"That's the editor's problem. Send it in—they can always cut it if they can't work with it."

"Okay." Molly accepted the papers back and flipped through them, skimming the notes he'd written in the margins. "Thanks for doing this, Sherlock. I really appreciate it."

"I'm glad to see you publishing again. You should do it more often."

"It isn't published yet."

"It will be."

She smiled at his easy confidence and laid everything aside before joining him on the sofa.

"What are you doing for Christmas this year?"

He made a face. "My mother insists on hosting a family celebration. She says I owe her for getting shot."

"That will be nice."

"No, it will be nothing short of torture. Mycroft will be there too."

Molly poked his thigh with her foot. "You have a family who cares about you. You should be grateful, Sherlock Holmes." He missed the allusion to her orphan status, and she let it slide.

"What about you? Are you working?" he asked.

"I'm on call the twenty-fifth, but there shouldn't be any problems." Especially if Sherlock and Mycroft were out of town under the supervision of their mother. "Meena has invited me to have dinner with her and her family, but I haven't decided yet."

"You should go," he said. "You'd have a good time. Better than just watching the Beeb with Toby."

"I don't know. I like Meena, but I've never met her family before."

"I'd invite you, but…."

"Oh, that's all right," Molly said quickly, understanding—even if Sherlock didn't—the implications of him inviting a woman home for Christmas. "Your mother's right. A family celebration this year is best."

"It's not that," Sherlock said. "If all goes as planned, I will be working."

"A case? On Christmas? Sherlock," Molly protested.

He said nothing, not even to scoff at her sentiment about the holiday. There was only one case he'd been reticent about this year.

"It's Magnussen, isn't it? I thought you gave that case up."

"Of course I didn't give it up," he said, leaning to the side as Toby approached the sofa and jumped up between them. "I just had to wait for the right opportunity, and it happens to be on Christmas Day."

She sighed, stroking Toby's head as he draped himself over her legs. "Well, I want you to be careful. He's—if even half the stuff that came out in the inquest is true, he's a dangerous man, Sherlock."

"So am I."

Looking at him now, the set jaw, the resolute expression, Molly believed it. Still….

"Promise me you'll be careful."

Sherlock relaxed, turning his back into the corner to face her. "John will be with me."

"Fine, then I want the two of you to be careful. Wait—John's going to your parents' for Christmas?"

He nodded. "He and Mary both."

"Both of them? Mary didn't say. Well, that's good, isn't it?"

"Eh. He's been less moody but still unusually quiet. I think he's finally prepared to forgive her."

Molly squealed. "You think the two of them will get back together?"

"Don't tell Mary—John hasn't actually said anything."

"I won't. I wouldn't want her to be disappointed. She's been miserable these last few months, though, even with her excitement about the baby."

"So has John." Sherlock sighed. "But I have enjoyed having a flatmate again."

Molly smiled. "You two just need to figure out a new routine. You're Sherlock Holmes, you'll come up with something."

()()()()

Mummy left the kitchen to take Mary her (drugged) tea. Sherlock noted the time on his wristwatch, then folded the newspaper he'd been reading and tossed it onto the table, hiding the headline of Lord Smallwood's suicide. He would like nothing more than to rub his arrogant brother's nose in the results of his so-called "protection," but Sherlock's plan to end Magnussen's power over others today depended on Mycroft's lack of suspicion. And Wiggins's calculations, and John bringing his gun, and Magnussen honoring their agreement, and Sherlock's own deductions about Appledore, and the information Mary had supplied, and myriad of other factors out of his control. It was a highly dangerous, unpredictable, yet necessary course of action, and one which Sherlock was determined to see to its conclusion, whatever the results. Ironic, that Molly Hooper knew him better than his own brother.

Ironic, but not surprising.

Sherlock double-checked that Mycroft was preoccupied with his inspection of the Christmas sweets Mummy had left unguarded on the table and slipped his phone out of his pocket. It had buzzed earlier, but Sherlock had not needed to look at the screen to know who sent the text. Everyone who might text him on Christmas Day was already here; everyone except Molly. Sherlock punched the button to light up the screen and read her message.

MERRY CHRISTMAS, SHERLOCK! HUMOR YOUR MUM TODAY—SHE'S EARNED IT.

Molly had "decorated" her text with a smiley face, three smiley faces wearing Father Christmas hats, a cone-shaped party hat surrounded by confetti, and five Christmas trees. Sherlock felt one corner of his mouth turn up. She'd been deliberately ridiculous to make him smile. He thumbed a quick reply.

MERRY CHRISTMAS, MOLLY HOOPER.

Then, because Molly deserved the extra effort, Sherlock did something he'd never done before. He tapped the smiley-face button at the bottom of the on-screen keyboard and scrolled past an appalling variety of disembodied expressions, cartoonish hand gestures, and assorted animals before he found what he was looking for. With a final glance to make sure no one was watching (Mycroft was busy rearranging the tarts on the tray so it wasn't obvious one was missing), Sherlock added a single Christmas tree emoji and hit send.

Hours later, kneeling outside the glass walls of Appledore with his hair and scarf blown by the wash of the helicopter rotors, Mycroft's panicked voice bellowing over the speakers as the red dots of laser sights danced over Sherlock's face and chest, Sherlock had the cold comfort that at least he'd been kind in what was mostly likely his last interaction with Molly Hooper.