If Joan had been home on that particular Thursday, the conversation that began it all likely never would have happened.

Or, if it had, she would have objected strenuously to the entire thing, forcing Moriarty and Sherlock to be…at least a little more subtle in their insanity, thus preserving Joan's for a little longer. At the very least, she would have had a better idea of how much blame to assign each of the participants, rather than flooding the brownstone with a blanket coating of frustrated disapproval.

On Thursday, however, Joan had an appointment with her therapist. And though their infrequent meetings were not terribly high on her list of priorities, nor something she particularly enjoyed, after three days of her current living arrangement—waking up in a cold sweat at the slightest noise, finding objects that she knew had been in her room moved around the brownstone despite changing the locks again, going through antacids like they were candy (and it was entirely possible that Sherlock had switched them out with actual candy, for all the good that they were doing), suppressing her instinctive flinch every time Moriarty looked at so much as a butter knife wrong—Joan was practical enough to admit that some outside psychiatric help was probably her best chance at making it through the 'ten days, at the most' without an ulcer or a nervous breakdown.

And after 90 minutes of discussing, in depth, why being only reasonably sure that her partner's ex-girlfriend/murdering psychopath/criminal mastermind wasn't planning on slitting her throat over breakfast wasn't enough to have her screaming for the nearest witness protection program, and why she continued to let Sherlock put her into these absurd, dangerous situations, Joan felt as though she'd earned an extravagantly expensive coffee and a relaxing half an hour at one of her favorite cafes. Just a small, peaceful reprieve from everything before she threw herself back into the fray.

If Joan had been home, things might have turned out differently. But because she wasn't, Moriarty and Sherlock were left alone together on the roof for three hours; her painting an original work that she refused to show anyone, he tending to his bees.

Until the sound of a scalpel scraping the canvas distracted him, causing him to look over.

Moriarty smiled. "Too much yellow," she explained, holding up the blade. And indeed, when Sherlock squinted, he could see traces of the offending hue streaked on the sharp edge.

He frowned, recognizing the tool. "I feel it fair to warn you that Watson will more than likely take umbrage at your purloining her medical equipment for your work," he offered neutrally. "Particularly given that the item in question is a sharp implement, which, as I'm certain you've noticed, makes her ill at ease to see you holding."

Moriarty's smile grew. "As if you don't do the same on a regular basis," she pointed out, reaching for the paint rag on the rickety table next to her and cleaning the scalpel without looking at it. "And perhaps she'll be more inclined to share her tools once she learns that I intend to give her the painting once it's completed. I am painting with her particular aesthetics in mind, after all."

Sherlock turned away. "Personal experience is how I know she'd thoroughly disapprove of having her medical bag rifled through," he admitted, unembarrassed. "And Watson has a rather stringent set of parameters regarding her possessions and their whereabouts—I'm not certain that your intentions regarding her kit will trump your failure to request permission to use it."

There was a pause. Then: "I will admit, the portrait you did of her was exquisite. An excellent likeness, especially when one considers that your in-person acquaintance had, at that juncture, been quite trifling."

Moriarty added a small amount of blue to her brush and went back to work. "Thank you," she said simply. "I'd be happy to have it sent here, if you like. The landing above the stairs is large enough to support the frame, and it could use some livening up."

"Of course," Sherlock continued, seemingly oblivious to the offer, "I was rather surprised that you chose not to paint her freckles, given that they're among the better—and more counterintuitive—of her features."

Moriarty paused almost imperceptibly. "But I did paint them," she answered, wrist moving delicately as she added details to the canvas that only she could see. "And then I painted over them, as Watson does herself whenever her schedule permits." She leaned forward, critically eyeing her brushstrokes. "Surely you've noticed that Joan applies a layer of concealer whenever you allow her enough time in the morning to indulge her vanities to an appropriate degree, before dragging her off elsewhere."

"With moisturizer and SPF 15 sunscreen," Sherlock confirmed shortly. "Except in the summer, when she forgoes foundation entirely and merely wears sunscreen."

Moriarty smiled at that. "And I haven't yet had the opportunity to know her in the summer," she pointed out. "I merely painted what was there—and exquisitely, as you said."

Sherlock's frown deepened. "Was it your first true original, then?" he wanted to know. "Obviously, you were working on something before your first…disappearance."

He made a face at that, as if the word was distasteful, yet necessary, in his mouth. "But I never did see it," he continued, "and I find myself less inclined to trust blindly than I was then."

"If that's truly the case," Moriarty wondered aloud, "what difference could my answer make to you? But no," she continued, "her portrait was not the first, though I do prize it as among the best."

She gazed past Sherlock, her glance sweeping out over the city. "Watson liked it, too, although she doesn't know that yet," she confided with a soft smile.

Sherlock tilted his head. "I thought her rather unnerved, actually," he disagreed, "though she took some pains to hide it. In another situation, I'd perhaps be more inclined to defer to your expertise—you having had a rather richer experience than I in reading others' reactions to your artwork—but I know Watson far more intimately that you do. She's not readily disposed to flattery in the way one might assume."

Moriarty raised an eyebrow. "My dear Sherlock," she replied, a hint of scorn in her voice as she turned at last to look at him, "of course she is. Subconsciously, perhaps, but our Watson is no different in that respect than anyone, you and I included."

Sherlock's eyes, which had narrowed at the mention of 'our Watson', were skeptical. "Even if you were correct in your observation—a premise with which I do not agree—behavioral expression is a much more accurate indicator of a person's feelings than any Neo-Freudian urge buried to the point of uselessness. Following your example, one could claim any number of unprovable things about Watson, and justify them in such a way that they defy validation or refutation. In short, you're cheating."

Moriarty put down her brush and crossed her arms. "Oh, Sherlock," she sighed, eyes narrowing to match his. "Is it really so hard for you to admit that I might know something about your…protégé, that you do not?"

Sherlock scoffed theatrically. "Seeing as your statement is an impossibility," he spat, "I don't see the point in admitting anything. You cannot match, in what amounts to maybe a week's worth of exposure, the knowledge I have accumulated regarding someone with whom I've lived and worked for nearly two years."

Moriarty didn't flinch at his agitated tone. "That," she stated evenly, "sounds distinctly like a challenge."

Slowly, Sherlock began to smile back.

If Sherlock had been consulted, he would have used Moriarty's final statement to blame the entire thing on her.

But what, Jamie Moriarty would have countered, did a staggeringly brilliant mind such as Sherlock's really expect from such a beginning?

The opening salvo was the book.

"Sherlock?" Watson called from upstairs. "What happened to the book that was in my room?"

Sherlock, who was sitting in the front room attempting to repair a television that was lately prone to losing the signal at inopportune moments, didn't look up from his screwdriver. "There are several books in your room, Watson," he yelled back, deftly replacing one of the screws in the chunk of metal he was holding. "You'll have to be a lot more specific."

He heard the sound of Watson's shoes clomping down the hall. "The one with the blue cover that was on the table," she elaborated, her voice significantly closer than it had been. "It was there this morning, and now it's missing."

"I put it in the drop box outside the library a few hours ago."

Sherlock turned at the sound of her voice—unseen by him, Moriarty had left the kitchen, where she'd been reading the newspaper, and was standing in the doorway.

Watson came far enough down the stairs to glare at her. "Why would you do that?" she wanted to know. "You didn't ask whether or not I was done with it yet—and that's not even getting into the fact that I've asked you a dozen times already to stop breaking into my room."

Moriarty raised an eyebrow in surprise. "But you were done with it," she pointed out. "You keep whatever you're currently reading in your purse, in case you have a free moment, or are on the train alone and need something to do. Except last night, you took the book into your room—there were only fourteen pages left, and you wanted to finish it. You kept your light on for twenty-seven minutes after closing your door, but didn't turn on your computer; instead, you restarted the final chapter to remind yourself what had previously happened, then finished the book."

Watson stared. "I don't want to know why you know that," she interjected.

Moriarty smiled. "Also, you had no intention of reading it a second time, though you enjoyed it," she added. "It was due tomorrow, and at nearly four hundred pages, you knew you wouldn't have the time."

Sherlock watched as Watson closed her eyes in exasperation, holding up her hands as if to stem the flow of deductions. "Whatever," she groaned, before turning and starting back up the stairs. "Just…ask, before you move my things next time."

Moriarty took a step toward the stairs. "The sequel's in your purse," she called up sweetly, and she and Sherlock listened as Watson's door slammed.

Moriarty looked over at Sherlock. "That was among the kinder of the reactions I had anticipated," she admitted, unperturbed. "There was a 3% chance of her throwing the sequel at my head."

Sherlock, who had been distracted from his work by the small scene, picked the screwdriver back up. "Watson wouldn't risk damaging the book," he informed her, adopting a disinterested tone.

Moriarty smiled anyway. "Sherlock. You can't possibly think your partner incapable of losing her temper in such a manner," she countered easily. "I'm sure you've driven her to worse."

Joan, determined not to give Moriarty the satisfaction of knowing…whatever it was the book incident was supposed to prove, deliberately avoided thinking about it for the rest of the day. She did not read three chapters of the sequel before going to bed that night, and she absolutely didn't have any trouble falling asleep. She remained serene and unmoved.

Right up until the moment the next morning when, wrapped in a towel post-shower, she nearly kicked over a pair of steaming coffee mugs that had been left directly outside the bathroom door.

"Sherl—" she started to yell, before cutting herself off—as long as Moriarty was staying with them, she couldn't blame every bizarre, ridiculous occurrence on Sherlock anymore.

Even if shouting at someone would have been somewhat cathartic.

Despite not finishing her yell, Sherlock bounded up the stairs and down the hall within seconds, as if he'd been waiting at the bottom of the steps for her call. "Yes, Watson?" he prompted expectantly, hands laced behind his back.

Joan gestured at the mugs. "What are these doing in the middle of the floor?" she demanded, readjusting her grip on the towel as Sherlock pointedly looked at her face and nowhere lower. "Because if they're for an experiment, you need to move them somewhere where I'm not going to kick them over by accident."

Sherlock frowned, puzzled. "I would have thought it would have been obvious, Watson," he chastised lightly. "They—"

He paused, then looked down, his expression changing to one of irritation. "Oh. Yes, I see. You're exactly right, Watson, and I shall dispose of this for you, post haste."

Bending over, Sherlock snatched one of the mugs off of the floor and strode off with it, leaving Joan with the second mug.

Before Joan had a chance to move, she heard a resounding crash come from the direction of the kitchen, one that sounded distinctly like porcelain shattering in the metal sink.

"Well, that wasn't weird at all," she muttered, gingerly sliding the remaining mug out of the way with her foot, then heading down the hall to her room to get dressed.

On her nightstand sat a second set of mugs.

The coffee mugs continued to follow Joan around all day.

In most of the rooms she went into in the brownstone over the course of several hours, there were pairs of drinks sitting on the floor, or on a table if there was one—one mug of coffee, one of tea. They were always piping hot and apparently freshly made, but as carefully and often as she listened, she could never detect the sound of the coffeepot brewing or the kettle whistling, and both appliances were cold whenever she went into the kitchen to check.

The drinks were occasionally accompanied by a scone on a plate, or a blueberry muffin on a stack of paper napkins. Joan hadn't even known that there were pastries in the house. Or more than a dozen coffee mugs in the cabinets, for that matter.

Sometimes, there was only one beverage in the room. Whenever that was the case, it never took Joan long to discover traces of the missing second—drips of coffee on the floorboards, the lingering smell of jasmine over a freshly-watered houseplant, more shards of broken dishware in the sink. After the third smashed mug, Joan gave up and left a dustpan and broom on the counter, carefully sweeping the broken pieces each time into a paper bag to be thrown out in the dumpster behind the building.

Throughout it all, Sherlock and Moriarty were suspiciously absent.

Both geniuses resurfaced just in time for dinner that night—takeout Chinese that someone other than Joan had ordered—and were on unusually good behavior, passing Joan soy sauce and napkins and pepper without prompting or commentary.

Neither one of them would openly admit to assailing her with beverages all day.

Openly admit.

"You do strike me as more of a coffee drinker when you have the option, Joan," Moriarty pointed out, delicately teasing out a clump of rice with her chopsticks. "Although separately, you really might consider adding a second teaspoon of sugar to your morning cup, the way the café on the corner that you prefer does—you enjoy it much more, and it's hardly as if a bit of added sweetness would do you any disservice."

Joan frowned, but Sherlock intervened before she could think of a reply. "Nonsense," he disagreed, sitting up straighter in his chair but continuing to look down at his food. "Although Watson does enjoy coffee, and with varying amounts of sugar, she prefers tea about seven times out of ten. Caffeinated before 5pm or if we're working on a case; decaffeinated if she anticipates going to bed at what constitutes a normal hour."

Joan looked back and forth between the two, both of them eyeing her with noticeable anticipation. "But neither of you had anything to do with today," she stated flatly, barely restraining the eyeroll that desperately wanted to come out.

Sherlock, at least, had the good grace to look very slightly ashamed of himself.

Joan sighed, folding up her mostly empty takeout carton. "Right. I don't think I really want to drink anything made by either of you right now," she admitted, before picking up her plate and napkins and taking them to the kitchen.

When the sound of arguing woke her up at 3am—whispers of "sabotage" and "sugar" and "blatant disrespect of sportsmanship" hissing their way through the air vent—Joan only listened long enough to ascertain that neither Moriarty nor Sherlock sounded angry enough to stab the other with a chopstick, before rolling over and going back to sleep.

Despite coming in at a distant third within the brownstone in the matter of sheer intellect (she hadn't decided whether Sherlock or Moriarty would win that contest, but she was certain that the minute she decided, the other would immediately deduce it and harangue her for it) Joan was far from stupid. She was well aware that some sort of dick-measuring contest was going on behind the scenes between Sherlock and Moriarty, and was also conscious of the fact that it had something to do with her.

She also knew that, being the only one involved with any sense of proportions or social limitations, she probably ought to put a stop to it sooner rather than later.

However.

Between the low-grade terror of having a mass murderer with an understandable grudge sleeping in the room off of the kitchen, everyone in her life who knew the relevant details being extremely (and loudly) concerned about her sanity—her therapist had recommended a nice, long tropical vacation, and various members of the NYPD had supplied her with no less than six panic buttons—and the minor veiled threats that were quickly becoming the norm—"Do you like turtle soup, Joan? I remember Sherlock and I having dinner at a Singaporean restaurant in the West End that specialized in it. I've had better, but he enjoyed it."—Joan's nerves were fraying nearly to the breaking point. And while it was incredibly disturbing to have that much attention paid to her every move, whatever was going on was clearly keeping the two of them distracted from other, almost certainly more disturbing plots.

Plus, the benefits were nice: warm, clean towels in the bathroom every time she went upstairs for a shower; exactly the right coat and shoes waiting by the front door every time she made to leave the house; precisely the meal she would have chosen for breakfast, lunch, and dinner, before she even knew that it was what she wanted.

Sherlock even bought a new, sharper blade for the blender in the kitchen, something he'd been promising to do for weeks but hadn't ever followed through on.

"I decided it was time, Watson," he announced while proudly showing her the repaired blender, six mornings after Moriarty's unexpected arrival and three days since both of them had begun being abnormally considerate of Joan. "You've taken to running more and longer than usual over the past week, and if this trend continues, you'll need additional fuel to replenish your diminished glycogen levels."

Joan smiled at him, genuinely pleased. "Thanks, Sherlock," she offered, peering inside the blender at the incredibly shiny blade. "I haven't been buying too many smoothie ingredients lately, but I'll have to stop at the market later and see if they have any—"

"Blueberries?" Moriarty interjected from her place at the counter, where she'd been sitting with her cup of coffee, watching the entire interaction. "There's a fresh pint in the refrigerator, as well as some spinach and strawberries from the farmer's market." She smiled dazzlingly at Joan. "Have you tried adding greens to your smoothies? It's an excellent way to add them to your diet, and it doesn't affect the taste at all."

"Which, of course, is only made possible by the presence of a blender in the first place," Sherlock added, shooting a cutting look at Moriarty before smiling at Joan as well. "The salesclerk assured me that the blade will outlive its warranty, but I saved the receipt in the event that he was incorrect. Now—"

"One could always make a salad with fruits and vegetables," Moriarty mused, her nonchalant tone betrayed by the fact that she'd interrupted Sherlock in order to use it, "thereby bypassing the blender altogether."

"Nevertheless," Sherlock replied, his voice clipped, "you wouldn't have thought to purchase them in the first place had it not been for the blender." He nodded to himself, clearly satisfied by his point.

Moriarty sat up on her stool, eyes sparkling.

Joan put the blender back on the counter. "And that's my cue to leave," she said, backing up toward the doorway. "Let me—actually, no, don't let me know when you're done with your little spat. I really, really don't want to know why the two of you have been making me your lab rat this week; I'll probably never sleep again."

Both heads whipped to look at her, nearly identical expressions of surprise on their faces.

Joan stared back. "You're not exactly subtle," she pointed out sardonically.

Moriarty, probably because she'd never been the recipient of a basketball to the head via Joan, was the first to recover. "Have you been having trouble sleeping?" she asked politely, settling back onto her stool. "I've found that memory foam pillows—"

"Of course you have," Joan grumbled, walking out and leaving a bickering Moriarty and Sherlock behind.

There was not enough alcohol in the world.