Big, hazel eyes stared up at him.

In fact they weren't big, they were enormous. Quite unnerving. Sherlock swallowed dryly.

'John,' Sherlock started, voice low, quite unsure of what lay on the sofa in front of him. Shifting the ski goggles up his nose with a spare hand – encased in an oven glove – he felt the beaker in his other dangerously wobble. Hurriedly, he put it down on the table; if toxic chemicals were "a bit not good" for John, they probably weren't all that brilliant for a baby.

John, quite innocently, wondered into the sitting room, focussed on the day's paper. It took a while, but eventually he gave a violent double take – quite melodramatic, Sherlock thought contemptuously, trying to ignore his racing pulse. Scooping his gaze over the beaker and so-far unexplained ski goggles, John asked unsurely,

'Sherlock, did you grow a baby?'

'I thought she was yours!'

'If you are trying to tell me you've deleted the difference between the female reproductive system again – '

They both froze when the small child let out a gentle, startled sound, waving a hand absently in the air. Gaze transfixed, Sherlock breathed out,

'She's about a day old, isn't she?'

Nervously, John nodded. Ever so slowly, as if he were approaching a particularly docile crocodile, rather than a sleepy baby, Sherlock plucked up the luggage label attached to her wrist. Written in wonky capital letters were the words,

PLEASE LOOK AFTER THIS BABY. THANK YOU.

And then,

JM x

Turning it over, Sherlock read the name on the back.

'Amelia Pond,' he hummed, half out-loud.

'Sounds like a name from a fairy-tale,' John finished uneasily, as if the words weren't quite his.

Every fairy-tale needs a good old-fashioned villain.

'What now?'

'I'll ring social services.'

And John was, thankfully, John again sensible, dependable John, baby curved into the crook of his arm as he pulled out a battered Yellow Pages –

Until the small child started crying and he froze, unsure as to what to do with the writhing bundle of pink. Eventually, he waved Sherlock over.

'She wants feeding, I expect – hold her, will you, and I'll… What is it that babies eat?' John stammered out, looking cautiously at Sherlock. The man towered over the young child, his nose wrinkled in a mixture of confusion and disgust. The blank look he gave John suggested he had absolutely no clue what babies ate.

'Milk – isn't it? Warm milk. In a bottle – do we have a bottle?'

John thrust the baby towards Sherlock, who took her awkwardly, holding her at arm's length, as if she had some sort of infectious disease. After rootling through the fridge for a few seconds, he gave a loud tut and turned back to his abruptly incompetent flatmate.

'She's not a bomb, Sherlock. Didn't you have any little cousins or something you had to babysit?'

A raised eyebrow.

'John, that's what nannies are for.'

'Of course, I forgot you're so upper class you barely know how to walk. Look, hold her like – like a rugby ball.'

Another blank look, until John finally took an almost aggressive step towards him, limbs rigid with frustration as he re-organised the baby in Sherlock's arms; said baby gave a rather undignified squawk until she was resettled against Sherlock's chest, and John returned, this time to a cupboard, trying to flick through the tome of a Yellow Pages book at the same time as stopping an avalanche of Tupperware pots from falling on his head.

Slowly, vary wary that if he dropped the baby John probably wouldn't be all that happy, Sherlock settled on the sofa.

The baby smelt odd. Sort of sweet – almost sickly.

I suppose there are worse things it could smell of.

Cautiously, Sherlock unwound the luggage label from her wrist, rubbing his thumb along the marks where the brown string had barely left an indent on the child's skin.

Those hazel eyes were looking at him again. They had gone from unnerving to bloody terrifying all at once.

'Hello, um, baby,' he said quietly, coughing awkwardly as the child looked blankly up at him before reaching up to tug gently at a loose curl flopping over his forehead.

'Uh – ow. That rather – if you could stop –'

Slowly, he prised the child's fingers apart, releasing his hair from her grip – unfortunately, this started up a disconcerting bawling. Mouth running dry, he quickly gave up his right index finger to the child's ministrations. It – she, he hurriedly corrected himself. John would get cross if he caught him thinking like that; somehow he always knew – seemed appeased by that.

Quickly, however, she looked rather bored, and Sherlock cast his mind back to his own childhood. What had his nannies done with him? He remembered story-time, vaguely, from when he was little, and plucked up the first book he could find from the floor.

' "The investigation and possible homicide led police to the farm of Ed Gein. Because the farm had no electricity, the investigators conducted a slow and ominous search with flashlights –" '

'Sherlock. Absolutely no Ed Gein stories,' John called out from the kitchen, rolling his eyes as he heard Sherlock drop the book to the floor with a huff.

Staring down at the baby, who smiled up at him, he began quietly,

'You, baby, are…' He searched for the right words for a second, wandering what he'd wanted people to tell him when he was a kid. Eventually, he found it. 'You are going to be very clever when you grow up. You're going to be a rocket scientist, or a brain surgeon, or a police woman – oh, on second thoughts, forget that one. Don't become a police woman. You are going to be the cleverest girl in your class, and the kindest, and the prettiest, baby –'

'Her name's Amelia, Sherlock,' John interrupted again, slamming the oven door shut with a noisy clang. He had found the pickled ears, then.

'Amelia is for fairy-tales. She's not an idiot. Amy's better –'

'Her name is Amelia.'

Sherlock's head snapped up to the door. A man stood there, bowtie skewed, hair messy, face wrinkled in distaste as he stormed up to Sherlock.

'Give her to me,' he snapped. He had a kind face – "kind face", something John would have said – but today he just looked tired.

'Who are you?' Sherlock asked, voice tight, a severe lack of trust running through his skin.

'The Doctor,' the man told him quickly, as if that explained everything, 'and that is Amelia – at least, for now, it is – oh Christ, I thought I told you to stay in the TARDIS?'

Ah. That's why the kind-faced man was so ultimately irritable. A four-year old peeked her head around his knees, staring up at him, face crumpled as if she were about to start crying.

'You two can't meet – you can't see each other – remember what I told you about space and time potentially being destroyed if you two –'

By now John had joined Sherlock in the sitting room. The Doctor trailed off when he caught the man's utterly bemused stare. He turned to Sherlock, looking for some sort of sanctuary, and instead found cold, narrowed eyes.

'Are one of you two Jim Moriarty?' He asked slowly, looking abruptly out of place in the doorway.

'No, we –'

'Amelia Pond, you get back here right now!'

The Doctor's cry was short-lived as the girl ran from one set of legs to the other. Staring up at Sherlock, they drank each other in. She was very small, and very skinny, with knees that looked as if they were about to poke through her skin. A big shock of red hair and a gappy, cautious smile as she looked up at the strange detective and the strange detective looked down at her.

'Is that me?' She asked the Doctor, looking towards the sleeping baby.

'…Yes,' he eventually sighed reluctantly. The little girl tugged on Sherlock's arm until he crouched, showing her the baby's tiny face. When she reached out an insistent hand, he pulled away slightly.

'No touching, remember?'

With a sigh, she stared at the baby for a moment, breathing loudly, before announcing, with a slightly disappointed air,

'I look weird.'

'Doesn't matter what you look like,' Sherlock told her sternly, eyebrow raised.

'But Auntie Sharon says –'

'Auntie Sharon is wrong.'

The words were simultaneous, coming from both him and the Doctor, leading the little girl to heave out an exasperated sigh.

'You always say that,' the girl sighed. Sherlock, still looking down at the baby, expected the statement to be directed to the oddly-dressed Doctor in the doorway – but when he looked up after an anxious beat of silence, he realised the little girl was staring at him. Slowly, he looked up to the Doctor in the doorway, who was pulling at his tie nervously and muttering something that sounded like, future me and present me need to have words, and the Doctor stood next to him, who gave him an utterly confused shrug in reply.

'Amy –'

'Amelia,' the girl interrupted him rudely.

'Amelia,' Sherlock forced out, twisting so he was facing the girl straight-on, eyes locked, 'how many times have we met. This is very important, so think.'

She tilted her head to one side and then eventually told him surely,

'Three times. There was the time with the jam sponge and Mrs Hudson, the Saturday with the skull and the evening with the pub when Mr Lestrade drank too much and got his –'

'You took her to a pub?' The Doctor and John snapped simultaneously, earning a scorning look from Sherlock that said, quite clearly, that he of course he hadn't. Yet.

'We have to get you two home,' the Doctor sighed tiredly, rubbing a hand across his eyes. Come on, Amelia one and two.'

There was a pause as the Doctor crossed the room and swung a papoose round his shoulders so it hung over his front, then held his hands out for the little baby.

'Do you promise to keep her away from Moriarty?' Sherlock told him sternly.

'Who?' The Doctor asked, already distracted – he was pretty sure Amy number three, the grown up one who was more trouble than these two kids combined, was waiting in the TARDIS. And a bored Amy number three was never good – and forgetting who the man was. Sherlock thought for a moment, then held out the luggage label, pressing it into the Doctor's hand. The Doctor swept his gaze over it, and let it crumple in his hand.

'Paddington Bear,' he muttered, 'very funny.'

And with that he was gone.

Sherlock looked around him for a moment, realised the four year-old Amelia had bent one of the pages on his book by stepping on it, then settled on the sofa.

He looked up at John who stood, slack-jawed, in the centre of the sitting room.

'Tea?'