The first time Sherlock said it, both men were caught completely off guard. They had just helped to close a particularly easy murder case and the Consultant Detective was fairly frustrated. They got out of 221B in a hurry because Greg had sent a message asking for help with an urgent case and Sherlock got overly excited thinking there was an interesting challenge on the way. But, in the end, it took only ten minutes of analyzing the room for the genius to identify the murder, the reason, where the weapon of the crime was and where the murderer was hiding. Greg set everyone in motion and, as the people around them started to evade the scene in order to catch the bad guy, Sherlock snorted. They left the now empty house while he went on a rambling about how these people were making him waist his precious time on such trivial cases and John couldn't bring himself to pay attention anymore. At least until the brunette sighed heavily and very casually said:
"Let's go home."
John's eyebrows immediately shot up in genuine surprise and his head turned around faster than they ever did before in his entire lifetime. His wide eyes met his partner's and he found out that Sherlock was equally shocked with his own words. The almost translucid blue eyes were carrying a confused expression that shouldn't fit the face of the mastermind of the deduction science, but was rather endearing actually. John wouldn't admit it out loud, but as Sherlock was used to know-it-all, when he truly failed to understand something (and it was usually emotion-related somethings), his expression resembled that of a little child facing something entirely knew. It was as genuine as humanly possible and absolutely adorable. In the middle of the arrogant prick attitude the Consultant Detective usually had, those rare moments were pure and honest and John always felt a warm feeling crawl up all the way from his stomach to his chest when that completely disarmed expression molded the delicate lines of Sherlock's face.
This time it was no different. But there was something more. The moment those last words escaped the brunette's mouth, John felt his heart skip a beat or two and then start to race madly to regain his pace. He struggled to maintain his composure under the crashing weight of that sentence. He knew he was not overreacting because of that damn cute face Sherlock was making. They never referred to the Baker Street flat as "home" before. Looking back, it was a matter of time. The dynamics of their shared flat (and their shared life for that matter) was nothing short of domestic and… homely. They argued about trivialities such as laundry, scattered objects, bullets flying at innocent walls and decapitated heads in the refrigerator. They enjoyed each other's company to the point that John would be in the room while Sherlock went through his unorthodox experiments so the man would have someone to talk to, to explain what he was doing, even though John wasn't interested in the least. Sherlock, in turn, would sit beside John while he watched the football games he loved so much. Of course the Consultant Detective would complain during the whole match bout how boring and idiotic it was, but he would not leave.
But, when what should be already obvious took the form of words, it surprised them nevertheless. It wasn't just the dangerously high levels of intimacy it revealed that caused the shock, but the fact that Sherlock Holmes was the one who said it first. Him, the so called sociopath, the totally-lacking-social-skills freak was the one who so naturally brought their relationship to a whole new level. It was the fact that a discrete yet distinct – very "Sherlocky" actually – shade of pink was tinting the brunette's pale skin as he became self-conscious of what he'd just said. Watson couldn't help but smile fondly at the man in front of him. He felt the urge to caress his partner (probably) silky and now pink cheek, because Sherlock was embarrassed and if it wasn't reason enough, he averted his gaze to the ground in an attempt to break the intensity of the moment they were sharing and in doing so, he hid his face partially on the scarf he was wearing and, for fuck's sake, Watson thought he couldn't get cuter! The almighty Sherlock Holmes was looking like a dear caught in the headlights and the gentle doctor was almost unable to keep his hands to himself.
Still smiling from ear to ear, John decided not to press the situation any further. It was crystal clear that the contours of the relationship between them were changing, becoming so much more than mere friendship and camaraderie, but he knew Sherlock wasn't used to emotions and feelings. He needed time to understand and adjust himself. From the moment they met until now, he had opened up so much that no one who met him before John appeared in his life would believe if they didn't see it with their own eyes. The thing was – Sherlock's brain was really fast, but his heart was really slow. And Watson was very much willing to take his time and ease his partner into this new territory called love. Because he knew himself and by this time he knew Sherlock well enough to know that this was what it was all about: love. John was no genius, but he was sensitive enough to understand how much they cared about each other and how unique their bond was. So he just patted the brunette's back in a comforting manner and answered as he waved at a cab passing by:
"So… home it is!"