A/N: Written for my sister, as my Sherlock fics are wont to be, when she was having a bad few days. Implied ace!Sherlock, biromantic!John, and blossoming romantic, non-sexual relationship. Or you could ignore the subtext and it's just them being themselves.

Disclaimer: I gladly disclaim, as I have no wish to be confused with Steven Moffat.

He didn't know what to do. He didn't know what to do, and that was very much Not Okay. He knew so much, so many things about so many topics. He could rattle off all sorts of obscure facts that had helped him with cases, and all sorts of facts that hadn't yet, but probably would, but here, he didn't know anything. And he could do so much, but in this area, he was inept. Terribly, woefully, disgustingly, frighteningly inept.

John H. Watson was Sick, and Sherlock Holmes had no idea what to do.

John had stumbled downstairs two hours late, wrapped in his dressing gown but still trembling violently. It had taken Sherlock all of five seconds to catalogue John's every visible symptom and come up with a diagnosis. John was Sick. Sherlock wasn't sure what kind of Sick, because that sort of thing didn't normally enter into his purview. Sherlock didn't get Sick, but, apparently, John did.

When John had completely rejected the contents of their refrigerator and every one of the cabinets, Sherlock realized John must be nauseous. That meant flu. It had to mean flu. What was one supposed to do to treat flu?

When John had leaned heavily on the counter, Sherlock knew that he had to get the older man off his feet. Sherlock left his perch on the couch and strode over to grasp John's arm.

"Wha—?" John had begun, but Sherlock had cut him off, knowing the other man wasn't going to say much of intelligence.

"Back to bed." Sherlock had been firm about that. He knew that if John needed the counter for support, he wasn't going to last very long in the upright position. So he had gotten the blonde to lie back down. That done, though, Sherlock had no idea what to do next.

Once he was prone, John's glassy gaze focused somewhat, and he blinked a little blankly at his flatmate.

"How warm am I?" John asked.

"I wouldn't know," Sherlock replied. "You're really the only one who can tell if you're warm or not."

"My forehead, Sherlock," John sighed. "Do I have a fever?"

"Oh." Without thinking, Sherlock leaned down to press his lips against John's forehead. "Definitely."

Even when sick, John could look extremely nonplussed.

"The lips are one of the most sensitive parts of the body, John." Fortunately, it was true, and Sherlock didn't have to admit that he had simply done the same thing his mother always had to check whether he or Mycroft had a fever when they were boys.

"Get me ibuprofen and some water," John instructed, accepting Sherlock's explanation. "And," he winced, "a bucket or pot or something."

Sherlock was gone and back with the things as quickly as possible. He didn't want to leave John alone for longer than necessary. Once he had set a rubbish bin next to John's bed and helped him take the fever reducers, though, he didn't know what else he could do. He stood next to the rubbish bin, hands clasped behind his back, biting his lip in frustration as he tried to think how else he could help.

Maybe John sensed it flatmate's dilemma, or maybe he truly needed what he asked for next. "Could you do something to distract me? If I keep thinking about how awful I feel, I'm just going to get worse."

"Distract, yes," Sherlock repeated, instantly knowing what to do. He bolted downstairs and was back in less than a minute with his violin. "Sit up," he instructed John.

The doctor pushed himself upright as well as he could, and Sherlock sat down on the bed, his back to the headboard, letting John's head settle onto his lap. John smiled and shook his head slightly, as if amused by Sherlock's actions, but closed his eyes as the younger man began to play.

Sherlock played softly, composing as he went, trying to turn emotions into song. The strings sang out safety and comfort, peace and love, everything he wanted to offer John, but couldn't find the words for. He watched as the blonde's eyes drifted shut, and played until John's breathing evened out and the ex-soldier was completely asleep. At that point, he put the violin down and set to stroking his hands through John's hair, something he had long ago discovered the other man greatly enjoyed, especially when asleep.

John slept most of the day. He threw up a couple times, and couldn't face eating anything until around midnight. Sherlock kept John hydrated, and paid close attention to John's fever, giving him more ibuprofen every six hours, ready to insist on going to the hospital if it ever reached a dangerous height. John occasionally found the energy to talk, but most of his time awake was spent listening to Sherlock play.

The fever broke at four in the morning. John was asleep at the time. Sherlock hadn't left John for more than three minutes at a time, and the continuous sitting had left him rather stiff. As he tried to slip out from under John's head, the doctor stirred.

"Favourite part of fevers, this," John muttered, glancing down at the sweat-drenched sheets.

"Feeling better?" Sherlock asked.

"Much, yeah," John replied, "and I'll probably feel even better after I shower."

"Just don't fall over," Sherlock said. "What was that?"

"Twenty-four-hour flu, probably," John answered. "And it's contagious. You might get it."

Sherlock brushed off his concern. "I don't get ill," he replied, and began to leave the room.

"Sherlock?"

The brunette turned back to his flatmate at the sound of his name.

"Thanks," John said quietly.

Sherlock smiled. "You'd do the same for me."