The worst part of parenting, John had decided, was the inescapable cloud of worry that followed him day and night. No one had thought to warn him that he would feel a slight tingle of anxiety for the remainder of his life. It didn't matter that the boys were sitting beside him on the sofa, all three of them drowsy from the rain and watching a film. It didn't matter that they had plenty to eat and warm beds and the entire British government at their fingertips should the need arise - which, he suspected, it never would. The potential threats were inescapable, the possible dangers infinite. He loathed the lack of control and he loathed his own parents for never giving him fair warning that all hope for inner peace would dissolve the moment he chose to reproduce.

Of course, part of the problem may have stemmed from his selection in life partners, but he'd long ago accepted the fact that that particular ship had sailed before he truly realized he was even on the pier.

Sherlock found his uneasiness amusing, a detail that didn't surprise him. While he was grateful in a detached sort of way for Sherlock's confidence in both his ability to parent and the general healthiness of their children, John tired of his lack of a confidant to share in his concern. Whenever he came to Sherlock with his apprehensions, he received a shrug and a derisive summation of the ill effects of unnecessary fretting. If he turned to someone else in his search for a sympathetic ear - Greg or Molly or, on one ill-advised and never-to-be-repeated endeavour, Mrs Hudson - the first reply always seemed to be, 'Have you talked to Sherlock about this?' He frequently considered throttling the man and starting the whole paternal process from scratch. The fantasy was not without its appeal; however, he doubted it would do much to alleviate his current fears.

Hamish didn't speak.

His fourth birthday was fast approaching. It didn't seem right that he had yet to utter a single word. Will had started early, already forming short sentences at ten months (although most of them had consisted of things like, 'No, Daddy!' and 'Biscuit now!' - hardly Shakespeare, but enough that his paediatrician had been impressed). By the age of two, they couldn't get him to shut up. He babbled to the constables at the Yard, the till girl at Tesco, cab drivers and carry-out owners and members of the homeless network. It seemed he'd befriended half of London before his third birthday rolled around.

But not Hamish. Hamish never made a sound.

He seemed a bright, happy child in spite of the fact. His eyes were wide and inquisitive, filled with utter fascination at every small aspect of life. He could laugh and cry, and performed the former on a frequent basis. He loved books, although John wasn't certain if he could actually read or just enjoyed the tactile experience of paper and ink and careful binding. He was warm and loving and spent every moment possible in the arms of one father or the other. John smiled as he recalled his son's first steps: nine months old (early; a good sign), standing without preamble and toddling over to him while he was deep in a book and leaning against his arm chair, how he'd flopped into his lap and stared resolutely at the pages. John hadn't thought for a minute before he began to read aloud. He'd spent most every evening since just like that.

Hamish made people uneasy. While their acquaintances seemed more than comfortable around Will (and how could you not, with his charming smile, his love of football, his natural politeness outside of 221B?), most everyone they knew approached Hamish with an air of caution. His calm stare was too much like his father's, his continued silence suggesting that he was sizing you up for later review. Harry pushed John to call a specialist and get him diagnosed. His check-ups showed no signs of hearing loss, but even John couldn't silence the internal list of possible conditions: autism, Asperger's, oral-motor dysfunction, APD, aphasia…

Sherlock, of course, was unconcerned. He spoke to Hamish as if it were perfectly normal for a child of almost four to remain mute. On the one hand, John was grateful for his obliviousness to the impending problems Hamish may face. At the same time, he grew more frustrated by the day.

But then Hamish would laugh or smile or curl against his chest. He'd nick Will's biscuits and grin while his brother went on a tirade. John would come home to find Sherlock in his chair, John's laptop and their youngest son precariously balanced on his legs, a string of deductions pouring from his mouth as Hamish's brow furrowed and he nodded in apparent agreement.

John tried to focus on these things. Like everything else in their lives, some days were easier than others.

When it finally happened, it was so subtle he almost missed it.

They'd been working on a case for days. Sherlock was in his usual state of sleepless, case-related starvation, his temper lightning-quick and his irritation seeping into the wallpaper of their flat. The wall above the sofa was a mess of push pins, papers, and string. Will had taken refuge upstairs, no doubt burrowed under the covers with John's missing laptop, immersed in some cartoon and a bag of crisps. Lestrade was planted in John's chair and looking like he needed a drink. John stood at the mantle and considered joining him.

The designer of their new décor was pacing and rambling, listing off the details of the case at a speed often reserved for well-paid auctioneers. John could feel the tension in the room elevate, Lestrade's frustration radiating over him with each new insult and grand declaration. It was clear the Detective Inspector hadn't slept in too long, his usual tolerance for Sherlock's idiosyncrasies having expired the day before. John couldn't blame him: a triple homicide was bad enough when the world's only consulting detective wasn't dragging your good name through the mud.

'Obvious, Lestrade! Obvious to anyone with eyes, let alone their other faculties! Why can't you see?'

'Fine! Bloody fine! But I don't see! What in God's name makes you believe a woman could have done this?'

'Most men don't wear perfume.'

'Thank you! Balance of probability! How many men do you know who wear Clair de la Lune?'

John wasn't listening to him anymore. The soft, high voice, the forgotten figure on the sofa, content with a book and still as a statue as he made his amazing declaration. John wondered if the world had swung out of orbit, if the weightlessness in his chest meant his organs had vacated his body.

'Oh my god.' He didn't realise at first that it was Greg's voice and not his own.

'Hamish?' The boy looked up, brows raised in curiosity, open and calm, as if this sort of thing happened every day. 'Did you-' He shook himself. 'How did you know that?'

Hamish pointed to a note stuck in the wall about a foot above his head. 'Clair de la Lune. Like Will's mum.'

'You- You know what kind of perfume Mary used to wear?'

'Daddy told us the story.'

John couldn't stop smiling. The murders were forgotten, the case before him far more interesting. He found himself crouching in front of the sofa, hand cupping the small, round face. His voice cracked. 'I didn't know you could talk, bean.'

Hamish shrugged, his smile warm and crooked. 'I didn't have anything to say.'

Lestrade sent a text only a few hours later: Subject apprehended. Headmistress at the vic's son's school. Your man was right again. Sherlock was pleased enough he didn't bother to complain when the boys requested an evening of pizza and Poirot DVDs.

It didn't take long for them to doze off: Will on his side with his head in Sherlock's lap; Hamish tucked into John's chest and grasping his jumper. They sat in companionable silence as Poirot expounded on the eating habits of the late Henry Gascoigne. Sherlock's fingers brushed through Will's hair, his other arm over John's shoulders. John distantly realised his mind wasn't racing, that his inherent anxiety hadn't made an appearance since that afternoon's momentous revelation. He put the thought away for now, resting his head in the crook of Sherlock's neck and listening to his faint but steady pulse.

'I was five.'

'Hm?'

'When I started speaking.' John's brows furrowed. He took his time to sit up so as not to disturb his sleeping son. Sherlock's eyes remained on the telly, his rich baritone barely audible over the soundtrack. 'Mother was terribly worried. She sent me to every specialist money could buy. They were convinced I had a learning disability of some sort.' His arm seemed to tighten around John's shoulder, fingers stroking his upper arm. 'One afternoon, Mycroft was in the parlour working on maths - algebra, I believe. I was reading over his shoulder and one of his answers was wrong.' His lip twitched on a smirk. 'I think he still wishes I'd never opened my mouth.'

John smiled, not realising his embrace pulled Hamish just a tad closer to his chest. 'So that's why you weren't worried. I thought-'

'I know. It's alright.' Sherlock turned to him then, eyes soft, the light of the screen playing across his pale cheek. 'I'm sure there's plenty else wrong with him that we'll discover. He is half Holmes, after all.'

John tried not to chuckle. It would only encourage him.