Irene had been surprised to get the text from Sherlock.

'Baker Street. Come at once. SH'

Intriguing hadn't quite covered it, and as she left her house in Belgravia she was torn between curiosity at what he might be about to say, and apprehension, because… Well… This was Sherlock. There were any number of reasons he could have called her to 221B, and most of them had run through her mind during the short drive to his flat… The actual reason, surprisingly, hadn't occured to her at all, not even for a moment.

"I need your help. With an experiment."

Those were the words which had greeted her as she entered the living room of 221B.

"I'm sorry?" Pausing in the door way, an eyebrow arched quizzically, she stared at the Consulting Detective, who was currently lying on the sofa, gazing up at the ceiling with his hands templed beneath his chin. This was… Unexpected. And completely baffling.

"An experiment," he repeated with a small sigh, turning his head to gaze at her. "I need your assistance with one of my experiments…" He watched her closely, his face as impassive as ever, though the slight twitching of his fingers, betrayed his nervousness, if anyone had been watching closely.

"O…K… What do I need to do?" He didn't answer, simply got languidly to his feet and moved steadily towards her, his gaze never leaving hers, the intensity of his stare sending slight shivers down her spine. "Sherlock?"

"Do you trust me?"

"Trust..?"

"Yes. Do you trust me?" She gazed at him steadily for a few moments, a thousand questions sparking in her eyes, before simply giving a short nod. In truth, Sherlock was one of the few people she did trust, whole-heartedly. But that didn't mean she wasn't both confused and wary about what he wanted her to do. He smiled as she nodded, his lips quirking upwards at the corners. "Good. Now close your eyes. And trust me," he added, his tone mildly exasperated as she opened her mouth to say something else. Clearly confused, she nevertheless did as he asked, a faint frown creasing her forehead as she waited.

Gazing at Irene as she stood patiently with her eyes closed, Sherlock took this rare opportunity to study the woman without having to contend with her own, piercing grey gaze. Her hair was curled loosely around her shoulders today, her make-up minimal; clearly she hadn't had any clients. Good. This thought surprised him, but he didn't examine it too closely; he wasn't sure he really wanted to, in all honesty. She was he noticed, however, wearing a very faint shade of pink lipstick. The red suited her better...

As the minutes stretched out, Irene's frown deepened, and Sherlock's resolve weakened. It had seemed like such a good idea at the time, and he hadn't thought too long on the reasons behind his desire to perform this particular experiment. But something had to be done. Sherlock needed to know one way or another, needed to confirm his suspicions… He was shaking, the small part of him which was actually interested in this as a scientific experiment noted, and ignoring the jumbled mess of chemical formulae and equations which flashed through his mind at that thought, he took a deep, measured breath and leaned forwards, hesitantly, to kiss her.

Skin touching. That was all kissing really was. So why did Sherlock now feel as though his nerve endings were on fire with a delicious, intoxicating, warmth? It was as though his mind had short-circuited; everything began and ended with the woman he was kissing… And who was now kissing him back.

Somehow, his hands had moved of their own accord and were pulling her closer, their kiss becoming more passionate as he wrapped his arms around her, though whether to shield her from an as yet unspecified threat or simply to make her his he wasn't quite sure. Sherlock felt as though he was in free-fall now, his thoughts becoming more confused and erratic as he scrambled to stay in control. The scariest thing was… He didn't hate it. He wasn't in control of… Well, anything, and he didn't care. And that thought absolutely terrified him.

Pulling back abruptly, he took a step away from Irene, before taking another step just to be safe; his entire body was now loudly demanding to know why they weren't still kissing and he didn't entirely trust himself not to do something else. But breaking the kiss hadn't stopped the deluge of feelings now coursing through him, and he was finding it difficult to regain his control.

"Well…" she murmured with a raised eyebrow, smiling faintly. "That was certainly… Interesting. Do all your experiments involve bodily contact?"

"No," he replied vehemently, glancing away, feeling faintly flushed.

"Really?" Her grey eyes danced with barely suppressed amusement as she gazed at him. "Does that make me special?"

"No." She laughed, her gaze flickering slowly over his face as she continued to smile at him.

"And did your… Experiment help your understanding of… Whatever it was?"

"N-No," he said quickly, shaking his head and blinking as he continued to stare at her. Liar his inner voice mocked. The experiment had shown him exactly what it had been designed to, even if it hadn't been the result he'd been hoping for. Damn it.

"Dear me, Mr Holmes. Your vocabulary appears to have deserted you." Gazing at him with undisguised amusement, she added, "I wonder why that is?"

Unable to formulate an appropriate reply to that, Sherlock simply turns away and goes to hide behind his microscope. Science. Yes. Facts. Nice, dependable facts, they were what were important. Facts like the molecular weight of sodium thiosulphate and the distinguishing features of different types of tobacco ash.

And the fact that Irene looked best with her hair down...

No. Wait… Not like that. Facts. He needed facts.

"Is everything alright, Mr Holmes?" He grunted in reply, quickly bringing his eyes to the eye piece and adjusting the focus. Not that he was particularly interested in whatever was under the lense, he just needed something, anything to take his mind off the dangerous thoughts currently swirling through his head. And science was safe. Science didn't leave him confused.

Rolling her eyes a little as Sherlock buried himself in his microscope once more, Irene was about to leave him to it when she noticed something. Biting back a laugh and turning to the overflowing desk, she spotted a slightly battered wooden box peeking from beneath a pile of papers and picked it up. Moving so she's standing just behind Sherlock, she leant forwards to whisper in his ear.

"I'm no expert… But I think it helps when you actually have something under the microscope to study." Placing the box of microscope slides on the bench next to him, laughing softly, she pressds a kiss to his cheek. "You know where to find me if you want to conduct any more… Experiments." Smiling at him, her eyes sparking with mischievous delight, she turned and walked out of the room.

Sherlock froze as he felt her warm breath in his ear, his heart clattering loudly in his chest, though he did his best to ignore it. At her words, however, he felt heat rush to his cheeks. Damn. She'd caught him out. And he was blushing. Why was he blushing? He never blushed…

Damn.

His mind short-circuited again for a few moments as she kissed his cheek, his blood singing at the contact, eliciting yet another dry scientific comment from the part of him which was still able to function, at the reaction of the human body to physical contact. Turning slightly in his seat, he watched over his shoulder as she walked away. Ah. Sentiment. What was it he'd told her? 'Sentiment is a chemical defect found in the losing side.' It appeared he'd been beaten again. Though, he thought with a small smile, if anyone were to beat him, he was glad it was her. Irene Adler. The Dominatrix who had oh so nearly brought a nation to its knees. The woman who'd beaten him.

The woman…