1.

Sherlock delicately moved the sheet of filter paper from the worktop and scraped the damp purple residue into a porcelain crucible, careful not to set off the volatile compound. His efforts were nearly scuppered, however, when the door to the living room banged open and John shuffled in looking distinctly dishevelled wearing a dark green dressing gown, his hair sticking out in every direction.

"I woke you," Sherlock said, glancing up and noting his flatmate's half-open eyes and exasperated expression.

"Great deduction, yeah," John retorted moodily. "What was all the shouting about?"

Sherlock returned to his dark red paste. "The ammonia annoyed me."

John rolled his eyes. "Of course it did," he said, resignation creeping into his voice. He gestured at the mess of equipment littering the kitchen. "What's all this for, anyway? We're not working on a case at the moment."

"Precisely," Sherlock responded, astonished that John hadn't made the connection. "I was bored." As he said the last word, he smacked his hand against the worktop and there was a small 'bang' and a miniature puff of purple smoke an inch away from where his hand made contact with the surface. "Oh, and apparently I spilled some," he added, observing John's jump at the explosion and the way his tired eyes flew open in alarm. "You might not want to come any closer."

If John's eyes were wide before this statement they could only have been described as great blue saucers of terror now."Sherlock, if this is dangerous enough to warrant a warning like that I think I deserve to be told what the hell you have been doing in our kitchen. What is that purple stuff?"

Sherlock waved a hand dismissively. "Oh, nothing to worry about, just some nitrogen triiodide." He paused for a second to glance at John, whose features were still clouded by an expression of incomprehension. Sherlock's own face lit up, he never turned down an opportunity to extol the virtues of chemistry when it presented itself. "It's a contact explosive, John! So volatile when dried you can set it off with a feather! You've already seen the reaction it produces and I'm sure you'll agree that it's absolutely intri..."

"So what you're saying is that you've cooked up some purple stuff that makes loud noises when touched?" Sherlock scowled at the oversimplification of the beautiful and fascinating science, but eventually conceded to nod. It was good to encourage John's ability to summarise, Sherlock acknowledged that this ability of his friend's often came in useful when he was trying to piece together the big picture out of smaller details.

"Indeed, John," Sherlock said. "The thing is, for the nitrogen triiodide to be explosive it must be dehydrated into crystalline form." As he said this, a pair of plastic goggles appeared in his hand from somewhere among the mess on the worktop, and Sherlock lit a match and held it over a Bunsen burner John hadn't noticed the crucible was being suspended over.

"You're not seriously going to put this extremely explosive stuff above a gas flame?" John asked incredulously.

"It's a few grams of contact explosive, John, not a block of semtex. Besides which, I'd rather like it to crystallise quickly so that I might proceed with having fun with it," Sherlock replied, before turning on the gas tap and turning his attention to the rapidly drying out compound in the porcelain pot suspended in the centre of the roaring flame. He barely had time to clap his hands and grin about how quickly it was drying out before there was an almighty 'BANG' and a huge puff of purple smoke, as the crucible shattered and the Bunsen burner (along with an assortment of other equipment) was thrown off the worktop, extinguishing itself due to the fact that its gas supply had been cut off.

Sherlock just stood in the middle of the purple cloud for a second, completely overwhelmed by the assortment of deafening noises, noxious fumes and unnaturally-coloured cloud. He was so consumed by the plethora of unpleasant sensations he didn't even realise he was practically coughing his lungs out until there were a few crashes and the hissing of the escaping gas disappeared. John's hand grasped his arm, dragging him out of the cloud and into the living room, miniature explosions under their feet adding to the din every time either of them stepped on a tiny amount of the dust Sherlock had clumsily spilled all over the kitchen floor.

However, as soon as the pair had reached the sofa and Sherlock had sat down, the smoke detector decided that the cacophonous orchestra of explosions and various instruments breaking as they toppled off the counters wasn't complete until it had added its own infernal beeping to the mix. Sherlock scrunched his eyes closed and clamped his hands over his ears in an attempt to shut out the world as the sensory war was occurring around him, but he still found that there was just too much going on for him to cope with.

Sherlock was dimly aware that in addition to the ear-splitting beeping of the smoke detector (which was starting to set off even more explosions by itself) and the pungent iodine fumes, the words "make it stop, John" were falling out of his own mouth, a desperate plea for his flatmate to make the bad sensations to go away.

He curled up on the sofa, hands still clamped to his ears, and after a few seconds he realised that the window had been flung open and the smell had gone away. Sherlock also observed that the end of the sofa he wasn't currently occupying was being stood on. Five seconds later the beeping went away and Sherlock opened his eyes to see his friend standing over him, nine-volt battery in hand.

"I daresay you can cope with whatever is left of the dust in the kitchen? Though honestly, after all that I'd have expected it all to have been set off," John said, as Sherlock sat up.

"I can handle that," Sherlock said, smiling uncertainly at John in gratitude.

"Are you going to be all right, now? Is it okay if I go and take my shower?" John asked anxiously, watching Sherlock as though he could return to his meltdown at any minute.

"I'll be fine. You take your shower," Sherlock responded, pressing his hands together to give himself something to concentrate on and prevent the immediate memory from overloading him again. John gripped his shoulder reassuringly before walking out of the door, and as Sherlock watched his retreating back he reflected on how lucky he was to have found a friend like John Watson.