"What's that, then?"

"Hm...?" Sherlock finally looked up from checking his new watch—or at least, what had first appeared to be a watch, but John had begun to notice over the course of the last hour or two that it seemed to be a lot more technical than that.

"You've checked it at least five times this morning. Looks like one of those... y'know..."

"Fitbits?" Sherlock supplied easily, glancing over at his friend, who was seated in his armchair, hair still ruffled from sleep. "That's because it is. I got it yesterday."

"The hell do you need an activity tracker for?" John frowned slightly.

Sherlock just gave him a look and paced over to the living room table, sorting through some of the piles of stuff. "It's an experiment."

"An... experiment?"

"Yes." He turned his intense gaze on John yet again. "A scientific enquiry? A set of circumstances set up solely to prove or disprove a hypothesis? A way of—"

"I know what an experiment is, Sherlock. I just... don't see what you could possibly be trying to prove..."

"I'm... curious." The consulting detective paused a moment, his eyes straying to the sleek black band around his wrist again. "I know how the body functions, how much energy it should expend, exactly what it requires... but I thought it would be... fun to see that in action. I have a body after all, even if it is mostly just to carry my brain around, but that's beside the point."

"O...kay..." John nodded slowly, reaching for the cup of coffee he had forgotten about on the table beside him.

Cold, now...

Wait...

John stopped, with the cup still raised to his lips. "Was this... in any way inspired by that case we had last week? Y'know, the one with the guy who, em... the one who was killed by being starved to death?"

"Might have been..."

"You're not going to do that, right...?"

Sherlock rolled his eyes, letting out a heavy sigh. "Obviously, I'm not. I'm just curious. Don't be absurd."

"Alright, alright... just asking..." John made a face as he tried another sip of his cold coffee, knowing full well that it would be awful. "Fancy another case, then?"

"Starving for one."