This didn't end up the way I thought it was going to - my very great thanks to MapleleafCameo for helping me find an alternative title to fit the story it became :)

It was no fun being the youngest in the family, especially when left in the care of an older sibling who, for whatever reason, found the necessity of looking after you a chore.

And it was this that the two unlikeliest flatmates found that they had in common, one night when a blizzard kept the criminal classes off the streets of London and they had discovered a 'filched' bottle of brandy stashed away in a bedroom...

xXx

"She used to go out and leave me on my own." John said to no-one in particular as he stared into the fire and sipped at a glass of Mycroft's best brandy, a bottle of which had been stolen some while ago from his Whitehall office by his errant younger brother.

The aforementioned brother was sitting in his armchair on the opposite side of the hearth, watching the firelight catch and change the rich colours of the liquid in his glass – also poured from the purloined bottle.

"Your mother?" he asked absent-mindedly as he twirled the glass in long elegant fingers.

"Harry."

"Oh."

Silence settled once more between them, broken only by the crackle of the fire.

"Mycroft used to lock himself away in the study rather than look after me."

John, who at this point had been on the verge of dozing off, looked across at his flatmate.

"Why?" he asked, surprised. "I thought he worried about you, constantly."

Sherlock smiled.

"Oh he does... now."

Sensing that there was a story to be told, John sat up and poured another small measure of brandy into his own glass and offered the bottle to his friend. Sherlock held out his glass, allowing the doctor to top it up with an equally small measure of the spirit.

"Come on then." John said after a few more minutes. "Don't keep me waiting."

"Stories by the fireside John?" Sherlock quirked an eyebrow.

"Can you think of anything better to do?"

Sherlock smiled and returned to his study of the rich golden liquid.

When at last John believed that no tale would be forthcoming he suddenly spoke.

"Mummy is a brilliant mathematician, and Father, well he always said he was the one that bumbled along in her wake..."

"I find that hard to believe..."

"Perceptive of you John – you'd be right too." Again that secretive smile flitted across cupid's bow lips. "Father is not a great academic, although he is by no means a stupid man. He is, like you, a conductor of light. Mummy used to take him with her to conferences and workshops. She attended loads of those when she was working on the mathematical theory that eventually was used to support the physics of the Large Hadron Collider."

"Really? Your mother...?"

"Why are you surprised John? I thought you would have realised that my family has a genius gene."

"As well as a modesty one – yeah sorry, I forgot." John's grin took the sting out of the words. "So they left Mycroft in charge then? No Nannies, governesses, tutors?"

Sherlock looked startled for a moment, then caught the teasing tone.

"This was the twentieth century, John, not the eighteenth." He rolled his eyes. "And anyway, Mycroft was always the sensible one."

"Right. Locked himself in the study." John shook his head. "Very sensible!"

"Hmm well, as I said, he used to lock himself away...until my experiment with electric effects on water."

Sherlock had wandered through the over-large cottage, looking for something to occupy his mind.

Father was assisting Mummy at one of her workshops. Sherlock really didn't understand the need for him to go along as Mummy was by far the cleverest person he knew, but she had said something about not having him there was like working in the dark, so Sherlock assumed this was why he was left with cake-face (although he wasn't supposed to call him that). Still, while cake-face had locked himself in Father's study, and while Sherlock wasn't actually saying it out loud to his (cake) face, then he supposed it would be alright.

That sorted, he wandered back through the cottage.

He could still find nothing that looked worthy of his time and effort without going directly against Mycroft's instructions.

"No, I will not play Pirates with you Sherlock, I need to revise for my A-Levels, now go away and find something to do that will not bring the house down around our ears or the fire-brigade to our door!" The older boy stalked towards the study. "You know how upset Mummy was the last time you did that."

"Wasn't my fault." The nine year old muttered to the closing door. "How was I to know that Father had lost the petrol cap for the lawnmower?" Silvery-blue eyes lit up however as he remembered the resulting explosion in the garden shed, and the fuss Mummy had made about his singed eyebrows and hair.

He thought about following and pestering Mycroft until he gave in, but the sound of the key turning in the lock stopped him, and with a shrug he wandered off to find something else to do.

He recalled reading in one of Father's Guardian newspaper science supplements about electric effects on water, so after listening at the study door to ensure that Mycroft was truly engrossed in his revision Sherlock headed to the kitchen.

He already knew that pure water is a poor conductor of electricity yet is not a perfect insulator as it always contains ions due to self-dissociation. His plan was to experiment with the passage of an electric current with the end result (hopefully) of causing electrolysis, and producing O2 at the anode and H2 at the cathode – beyond that he hadn't really thought it out, but set about collecting together the equipment he would need.

The first inkling Mycroft had that anything was wrong was the abrupt cessation of light coupled with a loud bang, followed almost immediately by a dull thud and the crash of falling china. Scrabbling frantically to unlock the door, Mycroft hurried from the room calling his brother's name.

Running through the darkened cottage he finally found Sherlock half sitting half lying, dazed, against the kitchen wall, surrounded by broken ornamental china.

"Sherlock!" Fright made Mycroft's voice harsh. "For goodness sake I can't turn my back on you for…."

And at that point the kitchen door opened, and in walked their parents, tired from their journey, concerned at the lack of light in the cottage and shocked to hear their eldest scion seemingly berating his younger brother….

Sherlock sat back in his chair and grinned.

"Mycroft never had a chance." He chuckled, holding out his glass for another refill.

"Oh, don't tell me – you played it for all it was worth, didn't you."

The younger man shrugged carelessly. "Why wouldn't I? He was always the clever one; I was delighted that for once he was on the receiving end of Mummy's wrath."

"So much for brotherly love!" John shook his head.

"Or sisterly love?" Sherlock shot him a questioning look.

"Yeah, well…"

"Harry!" eight year old John looked up at his big sister through tear-blurred eyes, his bottom lip trembling as he realised she had made up her mind . "Mum said you have to stay with me!"

"Yeah well, Mum won't know will she? 'Cause she'll be working 'til six tomorrow morning, and you ain't going to tell her are you?" Her face screwed up and ugly, sixteen year old Harry leaned down threateningly to glare at her younger sibling. "You know what I'll do to you if you do."

"Don't go, please." The little blond-haired boy begged, "I don't like being alone."

"I don't like being alone…" his sister mimicked cruelly as she made a plate of jam sandwiches. "What? D'you think I'm going to waste a perfectly good Friday night out with my mates sitting around looking after you?" Turning, she thrust the plate into the young boy's hands. "There. Don't say I don't give you tea before I go out."

"Girlfriend?" Sherlock enquired.

"One of many." John grinned.

"You don't seem too bothered, considering you were frightened, being left alone…"

"Nah, I can't hold it against her." Finishing his brandy John stared into the bottom of his glass. "I found ways of dealing with my fear of being alone, I discovered that actually, I could have control of the telly without having to watch the stupid programmes she liked to watch…"

"And…?"

"Aaaand…I frightened myself silly watching horror movies, ran up to my room, tripped on the stairs falling and breaking my arm," He grinned. "and while I was at the hospital I decided that I wanted more than anything else in the world to be a doctor."

"Does that mean I have to thank your sister for setting your feet on a path that ended with us sharing this flat?"

The consulting detective looked horrified, and John's grin became a chuckle – an infectious chuckle – and soon, warmed by the fire, and relaxed by the excellent brandy the flatmates laughed so hard at the thought of Harry's face as Sherlock tried to be nice to her.

In fact, they laughed so much that they didn't hear the footsteps on the stairs, or the light knock at the door before it was cautiously opened and a freezing cold, snow covered Lestrade stepped through and into the warmth of the living room.

Casting an eye over the occupants, he spotted the half empty bottle of brandy and the two glasses, and noted that they were both looking back at him while fighting off giggles.

"Jesus, I hope you two aren't pissed." He ground out, the cold and damp making him grumpy. "Some inconsiderate sod just went and murdered a club owner in Soho."

The hilarity died, and Sherlock and John exchanged knowing glances.

"The game," Sherlock declared softly, "is on!"