Watson burst through the door on the upper landing, nerves wired in anticipation, but masterfully calm and collected, exuding the same purposeful urgency of the battlefield. His eyes scanned the room with practiced efficiency. He stopped mid-stride.
There was Holmes, not prone on the floor somewhere as he had been expecting, but seated calmly on a rickety stool at the end of the blood trail Watson had followed from the entryway. He had one hand pressing a steadily-reddening cloth against his side, while he fumbled around in a box with his other. A bloody shirt lay discarded on the floor.
Watson stood in the middle of the room, watching Holmes pull a needle out of the box, hold it between his teeth, and then proceed to tug a tangle of string from his frankly ghastly first aid box. The absurdity of the situation rendered him speechless for a moment, and Holmes, for his part, had elected to ignore his flatmate. Watson cleared his throat pointedly.
"Holmes," he said, speaking calmly. "What are you doing?" The detective in question glanced up briefly, doubtlessly reading Watson's unspoken irritation in an instant. He dropped his gaze to the tangled string again.
"Obvious," he muttered through the needle.
"Obvious?" Watson questioned, as if he had had trouble hearing the response. He approached Holmes and leaned down to be level with his flatmate. "Oh! Obvious!" he shouted loudly, causing Holmes to look up at him again, expression unreadable. "Silly me!" Watson continued fervently. "For some unfathomable reason, I thought the obvious thing to do, when finding yourself injured, would be to seek the attention of the medical doctor you happen to have as a flatmate! Then, perhaps, he could attend to your wounds professionally, rather than you trying to do it yourself-" the indignation and derisiveness were positively dripping from his voice now- "resulting in shoddy workmanship and ignorant practices that will, in fact, exacerbate your recovery!"
Holmes blinked in the face of Watson's tirade, and a new, unfamiliar expression began to write itself across his features. Holmes seemed to be re-evaluating him. He appeared, oddly enough, impressed. As if he had suddenly gained a new-found respect for the doctor. Watson figured he would appreciate this later, but right now, with Holmes pressing a cloth to his side, holding a needle between his teeth, and slackly hanging onto a pathetically tangled and probably highly unsanitary piece of string, the doctor had other things to worry about.
"So," Watson continued, quieter but no less heated, "please do forgive my apparent lack of observational acuity, for I do not find your actions to be obvious, and allow me to repeat my question. What. Are. You. Doing?"
"I? I am..." Holmes seemed to struggle for a moment. "Merely testing you. Congratulations, Watson. Your medical instincts are superb."
"Indeed they are," Watson agreed immediately, with a firm nod. "As are my skills. Would you like a demonstration?"
Holmes released the tangled string, removed the needle from between his teeth, and dropped it into Watson's waiting palm. He grinned, suddenly and genuinely.
"Wonderful."