This fic is the result of an absolutely ridiculous exchange between me and J_Baillier one wet Wednesday morning, when we were wondering why Sherlock would have a supply of duct tape in 221b (to be used to tape up his plaster cast in Lunar Landscapes), and exactly what mischief he might get up to with it.

'What the hell?' John said, as he woke up in an uncomfortable position in bed, tried to move, and realised that he couldn't.

At least, that was what he tried to say. What actually came out was 'Mwh mwh mweh', due to the gag positioned over his mouth.

He lifted up his hands to remove it, only to discover that these were also restrained with what felt suspiciously like tape, and when he tried to twist to sit up he realised that his feet were similarly bound.

He lay very still, trying to assess the situation. His eyes were uncovered, that was something, but at the moment, he was afforded only a very good view of the wall that his bed was positioned against. He listened, hard. There was the familiar buzz of the traffic, poorly insulated against by the single-glazed sash windows of 221b, the hum of the central heating, but beyond that, if he listened carefully, was the slow, even breathing of another person in the room with him.

Somebody had tied him up, taped his mouth, but left him lying in bed, still covered by his duvet. What sort of strange, twisted intruder would do that?

He could think of only one.

He bent his knees up, struggling to gain purchase with his feet on the sheets, and with an effort, flipped himself over like a landed fish to glare at the watching figure sat in a chair in the corner of the room, stopwatch in hand.

'Mwah mwaffing mwastrd,' he managed.

'Oh, you're awake. Good,' Sherlock said, hitting the button on the stopwatch with an exaggerated gesture.

'Mwhh mwhh mwhhh,' John managed.

'Sorry, John, can't hear a word you're saying. I need to know how long it will take you to escape from the duct tape. Important part of a case.'

'Mwhhh...' John tried and then realising Sherlock would just claim to be unable to understand him, stuck to fixing him with his best glare.

'I'm not untying you. You're going to have to do it yourself,' Sherlock told him.

John closed his eyes and feigned sleep, hoping that Sherlock would get bored and release him when he realised that he wasn't going to play his games.

'In case you need any inducement,' Sherlock said, and reached over to turn on the tap in the small sink in the corner of the room. John's bladder twinged, and he realised how badly he needed a wee.

'Mwh mwe mwoh!' he spat out.

'Going to have to do it yourself,' Sherlock said cheerfully. 'Now given that you rarely last ten minutes before making your first trip to the bathroom in the morning, I suggest for the sake of your bladder that you hurry up.'

John glared at him again, then started to wriggle his hands behind him. It was thick tape - the proper stuff, none of your cheap imitations for Sherlock Holmes. He twisted his wrists against each other, remembering his hostage training that was standard for all British army personnel before deployment to Iraq. You couldn't break the tape, but there was a degree of give in it if you stretched it diagonally. Your first task, though, was to break the attachments of the adhesive to your skin. That was best achieved by moving your wrists through the full possible range of movement repeatedly, being careful to avoid friction burns. But you had to do this slowly if you didn't want your captor, or in this case, your bastard flat-mate, to realise what you were doing. His hands were behind him, and he continued to glare at Sherlock while he started to twist them against each other, ensuring that he kept Sherlock's attention diverted away from his hands.

Once he felt the adhesive give, he moved his wrists away from each other a few times, within the limits of the tape, assessing the degree of stretch. There was little, Sherlock had bound them tightly. How had he not woken up when this was being done?

'"Mwid mwoo mwug mwee?' he asked Sherlock narrowing his eyes at him, and then groaned, remembering the curiously vivid dreams he'd had. Of course, Sherlock had drugged him. He had thought it was suspicious when Sherlock had offered to make him a cup of tea. When would he learn?

'Sorry John, still can't understand a word that you're saying,' came the cheerful reply. 'I presume that you'd rather I didn't mention waterfalls or flowing rivers right now?'

Fucking bastard. It would serve him right if he freed himself and then peed all over his ridiculously expensive socks. Apart from there was the outside chance that Sherlock might enjoy that sort of kinky shit and John really didn't want to go down that road.

The bonds on his hands were finally loosening, and throwing caution to the wind, John decided to employ the technique of lateral stress, raising his hands up as high as he could behind him and then slamming them down repeatedly to try to tear the tape, as he had been taught, closing his eyes so he didn't have to look at Sherlock's smug face.

Eventually, he felt the tape start to give and then tear, and with a little more twisting to complete the job, he was able to wrench his hands apart and pull the tape off his mouth, just in time to interrupt Sherlock's 'Good, John. I'm impressed,' with a snarling, 'I suggest that you start running, Sherlock Holmes. Very, very fast.'

He threw off the duvet, thanking whatever powers were up there that he'd worn boxer shorts to sleep in last night, and attacked the tape on his ankles and lower legs. If anything, that proved even more tenacious than the tape on his hands. It wouldn't unstick and wouldn't tear. Growling with annoyance, he reached into his bedside drawer for his Swiss Army knife, and cut through it with that, careful not to nick himself in the process.

By the time that he had cut through the last of the tape and looked up, Sherlock was standing by the door, stopwatch still in hand. John ripped the last of the tape off his leg, giving himself a leg wax in the process, and launched himself at the door, but Sherlock was too fast for him, and the door was slammed in front of him. Then came the unmistakable click of the key in the lock.

'You are fucking kidding me,' he shouted. Then banging on the door with his fists, 'Sherlock, come on, let me out, I really need a slash.'

'It's all part of the experiment,' came Sherlock's voice. 'I need to see how long it will take you to pick the lock.'

John's answer was a string of expletives that surprised even him. The suggestion that Sherlock could take the lock and shove it up his arse was among the most polite of the suggestions that he made.

First things first, John went over to the sink, and keeping the taps running, had a long and fulfilling piss into it. Needs must when your psychopathic flat-mate had locked you in your room. Mrs Hudson would be horrified, but Mrs Hudson would never know.

Then, he turned his attention to the lock. Sherlock had helpfully removed the key, so the old stick a piece of paper under the door, jiggle the key free with a pen or similar, and slide the piece of paper under the door trick wouldn't work.

He put an eye to the keyhole and jumped back as it was met with a blue eye on the other side. 'You are a bloody psychopath, you know that?'

'Sociopath, John, sociopath.'

'How, exactly, do you expect me to get out of here?'

'Use your ingenuity.'

John used his ingenuity to plug the keyhole with several pieces of screwed up paper to obliterate Sherlock's view, and then after a quick scan around the room stood on the bed to remove the tiny camera from the picture rail. He found a second in the plant on his windowsill, and a third perched on the bookshelves in the corner of the room. Gathering them all up, he threw them unceremonially out of the window.

'You do realise that was about fifteen hundred pounds worth of equipment that you just destroyed?' Came Sherlock's calm voice from the other side of the door. 'Mycroft would be horrified if he knew that I had acquired them.'

'Let me out of this room, now,' John shouted, rattling the door handle.

'Can't do that, sorry. Like I said, I need to know how long it takes you to work out how to escape. It's for an old kidnap case I'm researching. The girl claimed she got out of the duct tape and picked the lock with no training in under twelve minutes. I think that she was in with the kidnappers. I need to prove that it's not possible to get out in that time.'

'You couldn't just have asked me to help?' John asked wearily, sitting down on the bed with a thump.

'It's more scientifically valid this way.'

John glared at the lock. The wood of the frame was old. One well-aimed kick to the bolt of the lock and the whole thing would shatter. But Mrs Hudson would be furious, and he didn't want to do that to her.

He was damned if he was going to play Sherlock's games, though. He looked at the sash window. It was two stories up, admittedly, but there was a fairly solid looking gutter outside he should be able to climb down, and the window ledge below was only a short drop down.

He was sitting on the sill, one leg out the window, preparing to climb out, when the door flew open.

'What are you doing?' Sherlock exclaimed, grabbing John by the shoulders and dragging him back into the room.

'Climbing out the window to get away from you and your ridiculous experiments. What does it look like?'

'Are you completely insane? Do you honestly think that one-hundred-and-twenty-year-old rusting Victorian drain pipes are going to support seventy kilograms of your body-weight? The shear factor alone...'

'Fine,' John said grumpily, swinging his leg back into the room. 'Now can you tell me what the hell this is all about?'

'I told you, I'm conducting an experiment into how people escape from captive situations.'

John sighed. 'And I should help you because?'

'Because if you do, then I'll clean the bathroom for the next month?'

'Sherlock, you have never cleaned the bathroom in all the time that we've lived here.'

'First time for everything.'

'Besides, Mrs Hudson cleans the bathroom. You'd probably use hydrochloric acid to try to remove the lime-scale from the bath taps or something.'

'Fine. I'll clean the fridge..'

'You could just promise not to out any more body parts in there?'

'They're important!'

'Okay, okay,' John sighed. 'Look I'll help you with your ridiculous experiment. Just no more drugs, and no more doing anything without warning me, okay?'

Sherlock looked awkward.

'What? Oh Christ, Sherlock, what have you done now?'

Exactly WHAT Sherlock has got up to, I'm afraid that I have absolutely no idea. I did consider ninjas, but apparently, that was taking it a step too far. If anybody has any suggestions then please let me know.

With thanks to ThessalyMc for the suggestions and betaing.

And with apologies to sevenpercent who told me not to do it ;)