It had been one of the strangest nights of John's life to date, and considering the fact that he shared a flat with Sherlock Holmes, that was truly saying a lot. After a fairly spectacular argument between the twins (which John had watched with a mix of fear and amusement) about where Katarina was to stay during the duration of her trip, the smaller Holmes finally won out, and Sherlock's bedroom had officially been coveted as her own, much to the detective's chagrin. After that had been settled, the luggage began to arrive, and John wasn't sure how such a seemingly down-to-earth woman could have so many clothes. Admittedly, at least three of the designer suitcases were filled with cameras and other necessary equipment, but at least four others were filled with an abundance of outfits for every sort of dress code imaginable, and John was briefly struck with the realization that many of the clothes were her own way of disguising herself, blending in with every sort of crowd. Finally, unable to handle the dark-haired duo's constant flip-flopping between bickering and half-internal conversations (apparently "twin telepathy" was not just a myth), he went upstairs to bed.

The next morning, John came down the stairs, a bit surprised to find Kate sitting cross-legged on the floor of the living room, an industrial-looking laptop in front of her. She was muttering to herself as she clicked on what looked like a blurry image on the screen, rendering it in an attempt to get some details out of it. "God damn it." She whispered in frustration, not turning to acknowledge John as he came down. Knowing better than to interrupt Sherlock when he was working, John decided to take the same approach with his sister, padding into the kitchen to find his flatmate, but to no avail. Nor was he in his bedroom or bathroom. Giving up, he came back into the living room in time to see Katarina slam her computer closed agitatedly, carding a hand through her short hair. Her angular face turned to him then, and she smiled pleasantly, "Oh! Morning, hon. Didn't hear you get up." John paused at her upbeat tone, having noted her clear frustration only moments before. She was already fully dressed in dark, perfectly fitted jeans and an emerald green blouse that exposed a tasteful amount of pale cleavage. She stood, stretching, her thin body just a bit taller than John's in the high-heels barely visible under the hem of her jeans. He had a hard time looking away.

"Sherlock home?" he finally asked lamely, watching her wearily as she scooped up her computer.

"Hmm? No, his friend called about some case. What's his name? The handsome inspector one…"

"Lestrade?" John asked, cocking his head in amusement.

"Lestrade! That's the one. I really ought to remember that." She shook her head, packing the computer away in a locking briefcase, snapping it closed.

"Er, right. Would you like to go get coffee, then?" he asked, feeling foolish. She turned to him and raised a delicate eyebrow, and John knew instantly what that look meant. He'd been rejected enough times to read the 'you're serious?' on her face. And besides, she was Sherlock's sister. His twin sister, to be precise, and just based on the way he had glared at him for staring the night before proved that Sherlock's protective nature shone through when it came to Katarina. "Just, you know, I didn't even know you existed before yesterday." He clarified awkwardly, and she smiled again.

"Alright, then."

After John had changed into jeans and a jumper, they walked a few blocks up the road to a little French bistro, where Kate chose a table under a striped umbrella on the patio. John, sitting beside her, studied her wearily out of the corner of his eye. It was still odd to him, how terrifyingly similar to Sherlock her looks and movements were, how graceful she was in even the smallest movements. The waiter came up to them and he could see it in his eyes too, the way people stared at her unique, hauntingly beautiful face. The poor boy barely even glanced at John as he took their orders (Katarina pronouncing her order with the smooth confidence of a fluent French speaker, making John's own tongue feel heavy and lame in response), and he scurried off again, leaving them alone.

"So…what's your story, anyway? I mean, most girls don't grow up to be, er, travel photographers." He glanced around, knowing her job was a top-secret one, and she smirked at his apprehension.

"How much have my brothers told you about our family?" she finally asked, smiling sweetly up to the waiter as he set their coffees in front of them before turning her clear eyes to John.

"Nothing, really." He admitted, wrapping his hands around the mug without actually drinking from it.

"Well, to understand my brothers and I, you really ought to understand our parents. I'm sure you've realized by now we don't exactly come from a modest household." John grimaced at that, knowing that nearly everything Sherlock owned was name-brand or designer. "Our parents were extremely old-fashioned, our father coming from old money, plus his position in the government, giving us more money than they really knew what to do with. Our mother didn't work, exactly. She collected old books, had a little shop, but it was more of a hobby. That was what mummy believed a lady should have: a hobby and a husband and children. And she believed those children should be well versed in everything. And thus my brothers and I were given the greatest possible education, learning math and science and language. I wanted to play sports. Mummy hated it."

She sighed then, taking a box of cigarettes from her handbag and placing one between her lips before offering one to John, who refused with a small shake of his head, dreading the moment when Sherlock would find his sister's stash. With a shrug, she lit it and took a long drag, and John struck by the grace she brought to what he generally considered a dirty habit. Waving her hand absently, she sighed a smooth stream of smoke, "Anyway. It's obvious, I'm sure, that my brothers and I exhibit what is generally considered a high amount of brainpower. We think differently, see things differently. Obviously the three of us excelled in our schooling, though it was just Mycroft who actually pleased our parents with his career; my parents do not even know that I work with the boys. They think I travel taking photographs." She grinned briefly, and John had to return the expression. "We look out for eachother, my brothers and I. That's why I remain anonymous, because they knew that in doing so I could have my best chance of a happy life. And I am happy, though more so now that I know my twin brother is being looked after. He worries Mycroft and I, you know." John nodded. He did know, he had known since he first met Mycroft.

The way she had said it though, that 'he was being looked after' made John hesitate briefly before deciding to ask the question that had so often passed his mind in his time with Sherlock, "So, er, Sherlock's never had any sort of friend or relationship or anyone before that would, you know, care for him?"

Kate chuckled darkly, taking another drag from her cigarette, "You know him as well as I do. Sherlock doesn't do relationships, or at least he didn't. Though I'm surprised you haven't had this discussion with him yourself, what with you two being together for so long."

John blanched, "Sherlock and I are not in a relationship." He said defensively, looking down as her eyes (his eyes) bore into him with a mix of confusion and amusement.

"Ah. One of those 'on-again, off-again' things? How very American of you." She stamped out her cigarette and took a sip from her coffee, smirking.

"No, one of those 'we were never on and therefore can never be off' things. I'm not gay, Katarina." John scowled, crossing his arms over his chest. Here he was, still harboring the slightest hope that this beautiful woman would be interested in him, and the entire time she had been under the impression that he was shagging her brother. It was humiliating, to say the least.

"But…that's not right at all, the way he talks about you…" her voice was barely above a whisper, full lips in a little O of surprise. "Oh, my poor sweet Sherlock."

"Excuse me? What the hell do you mean 'poor Sherlock'?" he was beginning to get angry and frustrated, hating the look of pity on her face.

"Yes, poor Sherlock. Poor Sherlock who is in love with a man so incredibly thick that he cannot even fathom the thought of a relationship with him. Poor Sherlock who shuts everyone out, but chooses to let in the one person who can, and probably does, hurt him the most. To love someone who you believe will never love you back…he's stronger than I give him credit for." She pulled out her phone then, sending a text with agitated movements.

"Sherlock isn't…he's not in love with me." John said, lamely, panicking a bit at her clear animosity.

"Oh? So he popped off a building because of his respect for your taste in jumpers?" she shot back, glaring now, protective.

"That wasn't just for me." He replied smally.

"How many phonecalls did he make on that rooftop, Doctor Watson?" she said darkly, standing as a black car rolled around the corner, and striding to the curb and into the back seat without so much as a second glance, leaving John alone and confused on the patio.