He knew what was going to happen, he knew what was happening, he knew, he knew, and he still wasn't convinced that it was—or that he wanted it to—right up until the moment that it did. He was both wholly expectant and utterly unprepared, and that first moment was so surreal that it happened seamlessly, almost as though they were accustomed to one another.
The bite of the stubble was strange, yes, he had expected that, or he would have if he'd let himself think about it—and the scent, he was vaguely familiar with that too, although Sherlock never let himself use any fragrance; said it might give him away at a critical moment. He couldn't figure out what was off until he shifted to ease a crick in his neck, and realized he was craning his head back. He wasn't used to kissing someone taller, not the taller of high heels or a step up on the stairwell but shoulders-casting-a-shadow-in-the-lamplight tall.
The kiss might almost have been called gentle; it certainly wasn't eager to go anywhere, and when John made the mistake of wondering what he was doing, the tension snapped into him so fast that the only thing that saved it from being horribly awkward was the cool steadiness with which things somehow paused. He opened his eyes—how long had they been closed?—and examined his companion from under lowered lids, gaze alighting on collarbones and jawline because he couldn't—quite—meet his eyes yet. It was then that he noticed the stillness, the strange body language that held Sherlock's torso at an oblique angle away from John, even as his lips hovered still inches away. Muscles tightly wound, under control, and John could feel the cautious gaze, assessing, analyzing, even now, when the only motion between them was his own chest rising and falling, a little unevenly but still, he thought, reasonably steady. He shook himself, a little, cleared his throat, went to speak but thought better of it, glanced up to meet the blue eyes quickly (which gave nothing away) before his gaze skittered off again like a nervous animal. The immediacy of the situation struck him then, the heat emanating ever so slightly from his partner's skin, the fluttering pulse visible below his jaw, their proximity, so close that he could make out the individual wool fibers in the collar of Sherlock's coat, which he had not yet removed.
He had forgotten to breathe. He sucked in air, all at once, almost choked, and Sherlock huffed out what might have been a laugh on a different man and came in for more. He didn't realize until later that there had been the slightest hesitation at the end, waiting for John to close the final distance of a hair, which he had done without thinking. When Sherlock's hand dotted off the counter for balance—they had both been leaned in oddly, and though Sherlock always moved with a calculated easy grace, John's trained coordination was better—it brushed against John's. Instinctively he moved away with an automatic "sorry," but he didn't wait for a reply before deliberately stepping in again, closing the distance between their torsos.
John tasted the faint tang of tobacco, and, startled, he pulled away. He met Sherlock's eyes fully for the first time, his stare accusing, and the taller man shrugged, feigning innocence well but for the slight guilty hunch of his shoulders. "Had to. Job," he muttered, and John was on the verge of formulating some retort about how as his doctor, he really didn't recommend—but then they were in again, moving against each other, and he had no idea which of them had started it that time, and he really didn't care.