John sighs and shakes his head. "I told you this would happen." Sherlock merely glares. "No sleep, no food and tearing around London will do this to you." Sherlock's expression doesn't change, and John smirks. "The great detective, brought down by pneumonia. Get some rest, okay?" And with that, he switches off the lights and leaves.

Sherlock's mind races, his eyes flitting around the room, looking for something to occupy him. It's no use John's room is surprisingly sparse, just a photo of Harry on the bedside, and the odd pulp fiction book. His room was far more interesting, of course, but John had called it a safety hazard and insisted he sleep in here. He tries to get out of bed, but instantly feels light-headed and nauseous. Instead, he settles for picking up one of the books strewn around, and begins to read. John is just dozing off on the couch, wondering how Sherlock could ever find it comfortable, when he hears him. "I'm bored, John!"
"Go to sleep then!" he shouts back. There is a sound like someone falling out of bed, and just a few minutes later, a paler-than-normal Sherlock looks into the room. John sighs, stands up, and hurries him back to bed, ignoring his wild gesticulating somewhat tempered by the way his balance seems to shift with every step and locks the room behind him.

Barely a minute passes and John can hear crashes and other such worrying noises from his room. Relenting, he unlocks the door to find Sherlock sat on the floor, throwing coat hangers across the room. "Really, Sherlock?"
"I'm bored!" John raises an eyebrow, and Sherlock practically pouts. He restrains himself from actually doing so, of course, because that would be childish, but John can feel the resentment from across the room.
"Fine. Look, I'll make you a deal." This time it's Sherlock who raises an eyebrow. "If I can find you something interesting to do, will you please just get some rest?" There's no answer, but John folds his arms and stares his roommate down. "Please?"
"Fine. But you won't manage it."

The first day Sherlock is cooped up in bed John brings him a selection of murder mystery films to watch. It's not long before he can hear them being flung around the room, with various exclamations about the obviousness of the plot, or how he'd got it before the first scene had ended.

On the second day, John tries a different approach, and suggests knitting. Two hours later, and Sherlock has made himself a new scarf and is throwing knitting needles at the wall, trying to work out the best angle to make them stick in the plaster.

The next day consists of Sherlock getting through the five most popular video games in record breaking time, before going back through them again and beating his own record. John begins to wonder if he'll ever work out some way to distract Sherlock from his boredom.

Day four begins with a pile of medical books bigger than John being left outside the door. It ends with a post-it note (where did he even find a post-it note, John thinks?) stuck to the top of them, saying Already knew everything in them. Bored.

On day five, John remembers something said in a conversation, snatches his keys from the table, and leaves the house in a whirl of inspiration. Sherlock cracks the password to his laptop (really, did John think Sher1ock_thisisMY_lapt0p would be difficult to guess? He was impressed at the use of numbers as well as letters though John was learning.)

It's day six by the time John returns, though Sherlock decides not to mention this, curious as to what idea had taken him so long to enact. "Here," John says, and carries in another pile of books, the top ones looking thin and colourful in comparison to the bottom couple, which could be used as doorstops. "I already told you, John, I know it all."
"Not this you don't." John hands him the top book on the pile with a grin. It's a picture book, and Sherlock raises an eyebrow.
"A trip around the solar system," he says, dryly. "This is a children's book." John smiles.
"Get reading." And with that, he leaves the room, locking it behind him.

Day seven passes quietly, and John spends the day pottering about, a half smile on his face. The smile gets more pronounced as day eight comes and goes. On day nine, he knocks on the door, and is greeted with silence. On unlocking it and stepping into the room, even he is surprised by what he sees. Sherlock Holmes, sitting up in bed, a notepad in one hand and the very last few books of the pile thrown haphazardly on the bed, biting his lip.
"Sherlock?"
"Wha...oh, John." His face lights up, his eyes sparking with the intensity John has only ever seen in them when a particularly interesting case turns up. "You'll be interested to know I actually slept last night."
"You slept?"
"Yes, I made you a deal, and I have to say, you surprised me this is fascinating. Now, would you be quiet and make me a cup of tea?" And with that, Sherlock returns to reading.

John doesn't have the heart to tell him he probably could have left the bedroom three days ago.