"Sherlock!" Nothing happens. The only sound in the apartment is a quite rattle somewhere on the other side of the door.
Sighing heavily, John puts down the grocery bags and digs his key out of his pocket. It wasn't like he expected Sherlock to get the door, the man would never dream of being that helpful. He turns the key in the lock, opening the door to the sight of Sherlock sitting on the couch, the object he is shaking in his hands becoming the obvious source of the rattling sound John identified before. Upon closer inspection, this object is a Ramune bottle, one of those japanese sodas with the marble inside. It appears that Sherlock has drank the soda inside, and is now shaking the bottle so that the marble produces a rattling sound with every movement of his hands.
"Seriously Sherlock, you couldn't be bothered to get the door because you were too occupied with a bottle?"
"Shhhhhhhhh," the detective hums, still focused on bottle in his hands.
"What in God's name are you doing anyway? Or have you finally completely lost your mind?"
"The answer to that, I would think, is quite obvious. I am shaking this bottle, and I lost my mind long before this."
The shaking sound still reverberating around the room, John grows quickly frustrated with his perplexing roommate.
"I can see what you are doing, what I meant was why?"
Sherlock looks up at him in that way that means John is stupid for needing to ask.
"experiment." He doesn't, apparently, feel the need to elaborate, because he looks back at the bottle and continues shaking, ignoring John entirely. John sighs and moves to put the groceries away.
Much later, as the moon rises high above the flat, John rolls over in his bed and jams his pillow over his ears. He can't sleep. All he can hear is Sherlock, still sitting on the couch downstairs, resolutely shaking the Ramune bottle.
Sometimes John thinks he is beginning to understand his brilliant flatmate. This is not one of those times.
