There were a few puzzled glances the first time Sherlock wore a tie to a crime scene since everyone was so used to his fitted shirts worn artfully unbuttoned, but since the tie was still loose, the top button of the shirt still unbuttoned, the change in dress was simply put down to some new eccentricity. It was a strange tie with a silver clasp over the knot and it couldn't be argued (for those who admitted to noticing such things), that the black against the white of the shirt and the pale of his skin with the reflecting silver was very striking.

And if John occasionally said, "Sherlock, your tie is a askew," and reached up to straighten it, to slide the silver clasp up until the metal touched Sherlock's long, white throat, well, that could be attributed to their strange relationship.

But it would have taken someone who was really watching, observing as carefully as a Holmes themselves, to notice that John only said it when Sherlock was being particularly unruly, lashing out with insults and derision, or vibrating with frustration at a particularly difficult crime. And only if one had made a study of Sherlock would one notice that when the metal pressed against his skin his eyes lowered, a certain defiant tension went out of his back leaving it more… What exactly? Not relaxed precisely, but more docile certainly. Then he would be easier to deal with, would wrap up his observations quickly and depart with only the slightest flourish of self-congratulation.

After the fourth or fifth such incident, John stopped straightening the tie and only needed to say the words, "Sherlock, your tie is askew," for Sherlock to respond. One would have had to have been standing right next to Sherlock, almost pressed against him, to notice that his breathing became shallow, his hands clenched and unclenched and a slight flush rose on his neck at the words.

John had given the tie to Sherlock as a present, earning a raised eyebrow for his trouble until he slipped it over Sherlock's head, drew the clasp tight and whispered, "On your knees, now."

Neither was sure who had suggested that Sherlock wear it out, specifically when called by the Yard. Who had decided that they needed a constant reminder of Sherlock on his knees naked but for the tie, the ends wrapped tightly around John's fist? But whoever it was, the end result was that when John tightened it at crime scenes both began running through scenarios in their heads until the need to return to Baker Street became urgent.

First, when the door of 221b was shut (and locked) behind them, Sherlock would strip while John held the leash, giving just enough slack for Sherlock to maneuver. But then…

Would John slide the clasp around to the back of Sherlock's throat? Push him onto his knees and fuck him roughly while tugging his head back, the band of the tie almost cutting off his air?

Would he push Sherlock onto his back? Spread his legs and take him while pushing the tie ends into Sherlock's mouth to make him gag on his cries?

Or, would he be more imaginative? Would he tie Sherlock's hands behind his back, artfully rigging the knot so that Sherlock's struggles would only tighten it, then make Sherlock watch as he masturbated? At last John would whisper, "Alright, 'Lock," release Sherlock's hands and let him stroke himself as John finished in his mouth.

If Sherlock had been particularly incorrigible, John would tie him somewhere, to the bedposts or the kitchen table, bind him in a cock ring and leave him there, struggling, aroused, cursing and angry, until he broke down, begging for John's touch, for John's forgiveness. Then John would come to him, untie him, take him to bed, whisper how much he was loved, how beautiful he was, how brilliant and amazing.