Disclaimer: I do not, nor will I ever own anything as cool as Sherlock.
The Difference
Contrary to popular belief, he heard everything. Just because he didn't acknowledge, or deign to answer at the time doesn't mean that he didn't hear you.
But that's just how people are I suppose. They confuse distraction with inattention and then lead the way with a self-righteousness that is neither warranted nor attractive.
But John knew better.
No, hearing was never Sherlock's problem. It's just time. Time. That's the problem, the enemy. Time. Blasted stupid illogically simple ridiculously complicated time.
If time wasn't so relative then it wouldn't seem like John was in the room only seconds ago when he had been away for hours. Time that makes it seem like hours, days, years, please please come back, since John left their bed when it's only been the few minutes for him to run down to fetch as glass of water.
And then there are days like today.
Days when five minutes is a year, an hour and eternity and the length of time that it takes John to watch a football match with Lestraude –no, not Greg, never Greg- and have either a few celebratory or consoling pints all the time that Sherlock needs to prove to himself the John has left for good. Gone, Gone forever Gone John.
Because who would want to put up with his brilliant thoughtlessness, his carefully constructed chaos on a continuous basis? But he had heard John say that he'd be back before too long.
Yes, Sherlock hears everything, but it's the listening thing that he needs to work on.
So in the length of time that it took to convince himself that John had never even planned on coming back in the first place because, seriously, who would even want to if he was what was waiting for him at home?
In the time it took for Sherlock to slowly migrate from his chair to the sofa, from the sofa to his mold spores on the kitchen table, from the mold spores to the bedroom and once on the bed curl up in a ball, all angles and elbow and ankle, he heard John coming up the stairs of their flat.
He heard John toss his coat over his armchair and gently open the door to their bedroom. Sherlock pretended to be asleep while he heard John undress. He heard the soft thud of John's jumper hitting the floor and the hushed hiss of his zipper as he left his trousers in a puddle on the floor.
He heard the mattress creak just the slightest as John crawled into bed and wrapped his arms around him and the soft shush of the sheet as it glided up John's legs, pants, t-shirt, before he finally settled in; his warmth passing through his shirt, across Sherlock's back and surrounding Sherlock with his scent. Stale cigarette, cheap beer, a small dash of cologne, and something woodsy, earth, musty and just so John that Sherlock simply wanted to drown in it.
The –pretending to be asleep- detective heard John gently sigh and felt the warm breath against the back of his neck.
"You heard me say that I'd be back."
Sherlock gave a non-committal grunt, hating that John could see through his not-so-awesome sleep acting and his insecurities.
"You'd be a lot less worried if you'd actually listened to me instead of just hearing me make noises that most people consider words."
"Most people are boring," Sherlock replied, giving up on the whole soundly-sleeping charade.
"Well, that's something that I'll never have to worry about in this relationship."
Sherlock gave a snort and John chuckled before they both drifted off into a deep, peaceful sleep.