His mind floats under the surface of consciousness, and for a fraction of second he has no idea where he actually is. Then a warm breath tickles his neck and he remembers, a lazy smile tugging at his lips as he revels in the feel of a solid body pressed against his back, and a pliant one curled up against his chest.
He listens to John's soft snore, absent-mindedly trails his fingers down Mary's spine. As unusual as this sleeping arrangement is, he can't remember an occasion when he slept better; he definitely enjoys the closeness, much to his own surprise, and he's not sure he wants to go back to his empty flat and the solitary life he used to lead.
It's only when Mary extricates herself for a quick trip to the loo that John stirs and presses a sleepy kiss to the back of Sherlock's neck. Soon enough they're wide awake, arms wrapped around each other as they engage in a throughout session of snogging.
"Mind if I borrow my husband for a while?" Mary taps him on the shoulder, and John reluctantly allows her to steal a morning kiss that promptly turns quite heated.
Sherlock takes his cue and pads downstairs. He can use a cup of coffee, and he may even consider surprising them with breakfast.