3. Gaming

Sherlock was lounging in his favorite fireside chair in the Gryffindor common room, having reclaimed it from a first year unfortunate enough not to know who it belonged to. Sherlock was upside down with his eyes closed, trying to work out a new potion in his head. His legs, lengthened by a recent growth spurt, were hooked over the back of the chair, and his head hung off the edge. He hoped the added gravity would induce some extra efficiency in his mental processes, but so far all it seemed to be doing was giving him a headache.

Over the summer he'd been reading various books on muggle forensics, which had piqued his curiosity. Particularly of interest to him had been the chemical called Luminol, which exhibited chemiluminescnece when mixed with the proper oxidizing agent. Basically put, it glowed blue when blood was present. It had turned Sherlock onto wizarding forensic techniques as well, and he was wondering whether it might be possible to create a potion that not only identified the presence of blood but also provided information on the person the blood had come from. It was tricky, and fascinating, and exceedingly difficult to puzzle through.

The polyjuice potion held some promise. It somehow analyzed a person's DNA and created a false image of them on another person's body. If he could discover its mechanism, perhaps -

A squeal of laughter interrupted him and he frowned, jolted from his thoughts. A sigh escaped him. He should have known better than to try to get any thinking done here. "Contain yourself John." He snorted unattractively as someone landed a flick on his nose and he struggled to right himself, prompting fresh peals of laughter from his friend. "How childish," Sherlock snarled, finally managing to sit up in the chair.

John didn't look abashed in the slightest, and merely rolled his eyes and turned back to the game of Gobstones he was playing with Lestrade. "Want to play the next round, Sherlock?"

"If the next round is wizard's chess and not Gobstones, then yes."

John groaned. "Merlin, no. I always, always lose."

"That's your problem. Seeing as how I am excellent at everything, I predict you will lose any game you want to challenge me at."

Silence. "Is that so?" John's voice was sly. "Want to try it?"

Sherlock waved his hand dismissively and closed his eyes, leaning back in his chair. "Why bother when I already know the outcome?"

"Aren't you always going on about how you need to test theories properly, or something? That sky-ents thing you're always talking about," Lestrade said around a mouthful of popcorn.

Sherlock shot him a look of derision. "The word you're looking for is science, Lestrade. I weep for the wizarding world."

John was grinning at him. "C'mon. One game, and I'll play wizard's chess."

Sherlock considered for a moment before rolling his eyes and sliding down onto the floor. Lestrade pushed his set into Sherlock's hands and he eyed the stones disdainfully. They were of varying sizes, some as small as blueberries and the largest one roughly the size of a ping-pong ball. Each Gobstone was filled with an evil-smelling liquid that sprayed the loser in the face, and Sherlock was keen not to get any of it on him.

He could do this. It was just a matter of physics.

Five minutes into the game it was clear he could not do this. John had knocked nearly all of his stones out already, and Sherlock's fringe was dripping with yellow, sulfury juice. Every time a new spurt of the foul-smelling stuff had hit his face both John and Lestrade had collapsed in howls of laughter, and Sherlock was bristling like a wet cat. New life goal: make John Watson pay.

He rolled his last Gobstone in his hand, feeling the weight of the liquid inside as it sloshed about. He had his eye on one of John's largest stones, roughly the size of a Snitch. If he were successful in knocking it out, John would get a massive dose of the stuff in his face. Sherlock grinned and knelt down, taking careful aim. With a flick of his thumb the ball lurched forward, heading straight for the stone. Sherlock bit his lip as the stones collided and the larger one began to roll out of bounds. At the last second it seemed to slow before finally toppling over the edge.

John threw up his hands in vain as the ball emptied itself, hitting him straight in his mouth. Sherlock smirked as John sputtered. Revenge was sweet.