"Hey," says John, just as Sherlock is about to spin off again, bringing him outside the reach of John's arms.
"Look at me." When Sherlock's head swings back to face John, John gently grabs Sherlock's chin between his thumb and finger and guides it down to John's level. John leans close, closer, and pauses, just long enough to make his intentions clear and then one beat longer, because let's be honest, this is Sherlock, who is occasionally Captain Oblivious. When he feels Sherlock's breath shiver just the tinniest bit, John's lips complete the journey. That tiny two inch space that really is the last leg of a much longer journey, of years of becoming flatmates, and friends, and soulmates in quick succession, without really noticing. Of ages of dancing around each other, pretending to not feel what both assumed were unreciprocated feelings. Of an eternity of waiting for this, a tiny kiss, a press of lips. Nothing sexual, nothing hurried, just a quiet statement; "This is a kiss. I am kissing you and you are kissing back because we have feelings for each other that extend beyond the reasonable borders of friendship into something scarier, something that has been delayed far too long."
It takes all his courage to open his eyes and look into Sherlock's gaze when John leans back.