"Have you got your keys this time?" John shouted after Sherlock as he flew up the steps to their flat. Sherlock smiled and waved his keys at John before turning and unlocking the door. "And how about you out the kettle on this time?" John added, knowing full well that he'd be the one reaching past the head in the fridge to get to the milk. Sure enough, when he got up the stairs, he saw Sherlock laid across the lounger, eyes closed, fingers steepled, coat flung across the arm of the chair despite the coat rack by the door. John sighed and walked towards the kitchen.
"The wounds were too bruised" Sherlock said without opening his eyes. John turned to look at his flatmate, a puzzled look on his face.
"What was that?" John said, spooning the sugar into Sherlock's mug.
"The stab wounds on the victims. The skin was too bruised for it to have been a sharp blade that caused the wound, meaning it was likely not to be a kitchen knife that did it – the blades are too sharp – which means that the killer brought the weapon with them, which means it was pre-meditated.
"Now, since we know it's a blade but not a kitchen knife, we can assume it's something commonplace but not necessarily something that everyone would have in their house. The woman and her sister have just fallen out – most likely about their father's poor health, most likely the woman wanted nothing to do with her dying father.
"We can then assume that the woman's sister wanted her out of the picture, so took her letter opener – sharp enough to open letters but not to easily pierce skin – to do it. And she couldn't leave her sister's apparently no-good boyfriend behind, so she killed him too and made it look like a robbery gone wrong." Sherlock opened one eye and added "just in case you were wondering"
John stood in the kitchen, a teaspoon still heaped with sugar in one hand, mouth hanging open. "How did you-"
"A letter from the hospital was on her desk. Do try to pay attention, John" Sherlock cut him off mid-sentence without opening his eyes "is the tea ready yet?" he added. John stirred the sugar into Sherlock's mug and brought both through to the living room. The silence between them was - once again – comfortable and complete.
John broke the silence after a minute or two "So that's what goes on in your brain, eh?"
Sherlock smirked and took a sip of his tea "The vast majority of the time, yes. Sometimes, however, it can be caught up in the tedious normality of brain patterns – like the need to eat and other such mundane tasks." John chuckled. "What's so funny?" Sherlock got up and went over to the window, picking up his violin and beginning to pluck at the strings.
John shook his head "you have a funny way of looking at things, that's all" he paused "so, you can work out whodunnit quicker than in a game of cluedo, but social cues are completely beyond you? How bizarre..."
"What do you mean social cues?" Sherlock looked at John incredulously.
John smirked back. "How many other people can point out other people's dirty laundry and unwittingly air it to the public?" he paused to take in Sherlock's stunned silence – something that was not often heard of from the world's only consulting detective.
"Even though you can be a bit of a social nightmare sometimes, Sherlock, you are kind of brilliant." John said, staring into his tea.
"Even if your brain is tiny and feeble, you do make an excellent cup of tea" Sherlock smiled at his flatmate and began to play the violin.