Giveaway prompt: Coffee

Sherlock glanced over at John, who was plugging away at the busy-work Sherlock had assigned him. They had to make it through this pile of lab notes in order to find the discrepancy between those stored in the computer systems at Bart's. The small detail, whatever it would prove to be, was the key to locating the lost inheritance of their client and his niece. The two flatmates had already been pouring over the tiny, handwritten notes for the past two days, working nonstop through the nights. (John had called in sick from work.)

A brief pause found John in the kitchen, making himself a beverage. Coffee, Sherlock guessed, before the rich aromas reached him in the sitting room. John drank tea to relax, but coffee to keep himself awake. This usually only ever happened during a case, as otherwise he was quite keen on getting his self-prescribed eight hours.