Sherlock rubs his eyes groggily as he sits up in bed, glancing at the clock and frowning, pulling his dressing gown around him and standing.

"John?" he calls out sharply, heading to the front room.

John looks up from where he was reading the newspaper on the sofa, hiding a smirk as he calls out back - "Sherlock?" - hoping to sound casual to add to his reaction at his changes to the flat.

John smiles warmly at Sherlock as he enters, taking in his rumpled hair and disgruntled expression and being vividly reminded of one of his cousins from when he was young.

"You're up early, is anything wrong?"

He doesn't want to start with the baby talk just yet, waiting instead for Sherlock's probably explosive reaction.

Sherlock's eyes narrow and quickly dart around the flat.

"John..." He mutters to himself. He takes in the array of soft cushions and blankets around the floor, looking over the rest before speaking louder;

"John, what on earth have you done?"

"Well Sherlock," John beckons Sherlock to sit beside him and is pleasantly surprised when he collapses next to him, "I decided that if you are going to act like a child then I will treat you like one. Until you learn your lesson of course, do you understand?"

For the first time Sherlock seems stumped and John pats his thigh reassuringly, "Any questions?"

"I don't-" Sherlock swallows in thought and frowns, looking around the room, speechless for once before eventually finishing in protest "I don't act like a child! You're being ridiculous!"

John stands in front of Sherlock, having already decided that even though Sherlock was to be treated like a baby, he wasn't going to be babied.

"You throw tantrums, you sulk, you refuse to eat or drink even though you know you should, you're incredibly rude and self centred, all very childlike traits. You want attention and I'm giving it to you."

He allows a little smirk to break through, "Now would you rather mushed banana or porridge for breakfast?"

Sherlock looks up at him, mouth slightly agape in disbelief before he stutters "I- this is preposterous!" he stands up and stares at him almost curiously.

"You're being serious, aren't you?"

John raises an eyebrow, and what he calls his 'army voice' takes over, "Do I look like I'm joking? If you answer me back again there'll be a punishment awaiting you. Now do you want the bananas or the porridge?"

Sherlock turns silent, thinking for a moment and observing John before realising that he was, in fact, deadly serious. He tries to ignore the strangely pleasant warm feeling in his stomach and sits down dejectedly and mumbles "Porridge", trying his best to look moody.

"Good choice," John leans over and smiles, brushing Sherlock's hair out of his eyes. He almost glares at John in instinct but instead something makes him look at him in a curious manner, eyebrows furrowed slightly. John heads for the kitchen where he heats up a bowl of porridge and prepares a bottle of milk whilst whistling to himself.

Sherlock hugs his dressing gown tightly around himself and crosses his legs on the sofa like a child, glancing at the changes to the room and biting his lip, confused at the almost delighted response something deep inside his mind was having.

John returns, balancing everything on a plastic Winnie the Pooh tray that Mrs Hudson had dug out for him, and sets it on the coffee table. He watches Sherlock, trying to not look nervous at his possible reaction to the bottle - as well as everything else he has yet to introduce.

"Right then, open up," he picks up a spoonful of porridge and brings it to Sherlock's lips.

Sherlock observes the tray from the corner of his eye, taking in the bottle and looking back at John, trying desperately to think of a witty retort as an attempt to hide away from his confusion towards his feelings in this situation, but instead ends up squirming slightly on the sofa and picking at his sleeves.

"Not hungry" he mumbles meekly

John sighs, "Come on Sherlock, it's not that much and it's good for you. I'm sure you don't want to disappoint your Daddy, or suffer the punishment for doing so."

John surprises himself with the 'daddy' but it comes naturally and he decides to go with it. He presses the spoon against Sherlock's lips, "Come on, that's a good lad."

He remains still for a moment before parting his lips and opening his mouth slightly, curling his toes without meaning to at the level of comfort he felt being fed by John combined with his use of the word 'Daddy'. He almost feels a relief, as if he had broken free from being just the detective and was getting the safety he'd always craved deep down.

John smiles and feeds him the rest of the porridge slowly and encouraging him with each spoonful. When the bowl is finally empty he sets it down and picks up the bottle, placing it carefully in his grip.

"Well done Sherlock, I know that must have been hard. Daddy's very, very proud of you. Now do you want Daddy to help you drink your milk or can I trust you to do it on your own?"

John is truly proud of Sherlock - a bit stunned as well, he'll admit - and a warmth and fierce sense of protection grows in the pit of his stomach as he watches Sherlock go over his reply in his own head He rubs his thigh.

"Come on baby, make a decision or I'll make one for you."

Sherlock blinks slowly at the bottle, a little dazed at his sudden change of behaviour and compliance with John after being so used to the 'dominant' role in their...friendship. He eventually speaks, not making eye contact and softly murmuring "Help me", expecting the word to feel uncomfortable and alien in his mouth but finding the opposite effect.

John smiles and takes the bottle from his hands "Alright baby."

He leans over, his still muscular arms easily moving Sherlock onto his lap and resting his head against his good shoulder. It feels calm and so right to be doing this, to have Sherlock so compliant and vulnerable John kisses his forehead before bringing the bottle to his lips.

"Drink up and then you can have your bath" he coos.

Sherlock feels soothed by the close proximity and warmth from John and somewhat self-consciously begins to suckle at the bottle, drinking down the warm milk. He feels vulnerable in the position he was in both emotionally and physically and doesn't make eye contact, still needing coaxing and reassurance.

John runs his spare hand through Sherlock's hair as he drinks, whispering encouragements and praise and telling him their plans for the day: a bath, a change (by which John means a nappy, and Sherlock probably presumes clothing), play time, lunch and maybe a walk through the park if Sherlock is a good boy.

Sherlock blinks and smiles to himself at John's tone of voice, now eagerly drinking the rest of the milk and nuzzling slightly against his shoulder. He breaks away after finishing, slightly breathless from his relentless swallowing and allows John to wipe his mouth clean.

John places the bottle back onto the tray, holding Sherlock for a long moment and nuzzling into his hair.

"Right come on then, lots left to do! I want you to go to the bathroom and strip ready for your bath whilst I tidy up and if you're not ready by the time I get there then you're getting a spanking, understood?"

He gets up quickly and mentally prepares a comeback which fades to a meek "Yes daddy" as he looks at John's stern face.

In the bathroom he looks at himself in the mirror, noticing the softness in his eyes as he tugs off his pyjama top and dressing gown, struggling and almost tripping over his bottoms in his childlike state of mind.

John tidies up quickly and heads to the bedroom first to prepare for after the bath, he lays a towel on the bed alongside a nappy, talcum powder and a fluffy dressing gown that is much warmer than the ratty old thing Sherlock usually insists on wearing. He then hurries to the bathroom, not wanting to leave his little boy alone for too long.

When John enters Sherlock is sat on top of the toilet seat, shuffling and embarrassed at his nakedness, looking up at him anxiously, feeling the pleasant warmth in his stomach return at his arrival.

John smiles at Sherlock, filling with joy when Sherlock nervously smiles back. He sets to work, filling up the bath and introducing Sherlock to the rubber ducks and plastic ships he bought for Sherlock to play with.

Sherlock takes in the toys in delight, reaching out for one and slipping out a slight giggle, observing it and smiling to himself. He feels as though he ought to speak but still remains comfortably silent, taking in the situation and watching John somewhat fondly.

John cannot help but grin at Sherlock's reaction and fascination, joining in with the play until the bath is full and at a decent temperature. They place the toys in the bath together then John picks up and places Sherlock in the bath too. He nuzzles his hair again, "There's a good baby."

He smiles to himself and bites his lip, looking down to play absent mindedly with his new toys, splashing about in the water and feeling content and safe. The role felt and came naturally to him, as if it had always been hiding, and the level of trust and care with John took away any feeling of foolishness.

His current mindset was so far away from his usual aloof, sarcastic controlling nature, and he felt comforted here.

John carefully washes Sherlock all over, taking care not to get soap in his eyes and reprimanding him when he splashes water all over John and the bathroom but he doesn't particularly mean it. Seeing Sherlock so happy makes John happy and he knows it's a happiness he'll do anything to protect. He's nervous for Sherlock's reaction to the next part of his plan and prolongs the bath for as long as possible.

Sherlock blinks water out of his eyes from his hair and notices the water growing cold. He rubs his eyes before wrapping his arms around himself, mumbling "Cold", looking up at John expectantly.

John sighs, "Come on then." He helps Sherlock out of the bath and into a towel then leads him towards the bedroom, "You've been such a good boy Sherlock, I hope you can keep it up for the rest of the day and not disappoint Daddy."

Before he can reply he spots the nappy, trying to figure out his thoughts on the idea as he cuddles up in his fluffy towel, following John and asking simply and innocently "Is that for me?"

John nods and smiles, picking it up and showing it to him properly, "Yes it is, and do you know what it's used for?" Sherlock nods and John indicates for him to lie on the bed, "Come on baby, you'll be needing to use it soon I expect."

Sherlock blushes slightly, the idea both humiliating and attractive to him. "Yes" he replies as he shuffles uncomfortably in his towel and tries to come to a conclusion on the idea. "I don't -" he frowns and looks at the floor, remembering John's earlier threat of punishment.

"You don't what?" John asks in his most soothing voice, wanting Sherlock to trust him with his worries even if John has to confirm them. He sits on the bed and pulls Sherlock onto his lap, "What's wrong, hmm?"

He nuzzles against his jumper for comfort. "Why do I need one?" he blushes and looks up at him "Will people know?"

"It's just one more way for me to take care of you Sherlock, and keep you safe and clean and I promise nobody will find out. I've even bought looser trousers for when we have to leave the flat, okay? The only way somebody will know is if you decide to tell them baby." John kisses his forehead and moves him to lying on his back on the bed.

Sherlock thinks over his words before nodding, calming down and enjoying John comforting him, sucking his thumb absently as he lays back on the towel obediently.

John makes sure Sherlock is thoroughly dry before sprinkling him with talcum powder and rubbing it in carefully. He exhales, checks Sherlock is alright before sliding the nappy under him and doing the tapes up tightly at the front. John slides his fingers around the leg holes to check they are secure before stepping back to admire Sherlock lying on the bed.

Sherlock rocks slightly and attempts to sit up, the padding making it difficult and he clumsily manages. He looks down at himself and feels his ever growing fondness and devotion to John swelling, the warmth of the nappy adding to his childlike state as he looks up at John, smiling weakly.

"Thank you daddy"

John smiles back, "You're such a good boy Sherlock, it's no problem at all." He helps Sherlock into the fluffy dressing gown sits on the bed with him, "Now what do you want to do for playtime?"

Sherlock looks up and around, face lighting up "The toys in the front room?" he cuddles up in his new dressing gown, peering around excitedly.

He laughs, "I knew you would have noticed the toy chest!" He lets Sherlock drag him into the living room and watches him pull everything out of the wooden box, "Anything you take out has to be put back Sherlock, I'm not allowing you to make a mess."

Sherlock nods and picks up a toy police car that catches his eye, smiling to himself at the context it's usually in and playing with in contentedly on the carpet, absolutely absorbed as John watches on.

John feels entranced by this side of Sherlock: he knows he should be doing the washing up or starting on lunch or replying to comments on the blog but he can't keep his eyes off of Sherlock and the chase scene he's creating out of toys. When Sherlock runs a fire engine into his foot his gives in and joins in with the playing.

He grins and encourages John in on the game. They sit playing for hours, Sherlock occasionally bringing more characters or completely dismissing it for a new game entirely, forgetting his adult side completely and giggling along with John, sat like a child with both legs sticking out.

Eventually John catches sight of his watch and the time. muttering, "Shit," he gets to his feet and ruffles Sherlock's hair, "Looks like time's gotten away from us baby. We've missed lunch time!"

Sherlock looks up, looking slightly disappointed and pouting "No more playing?" he ignores his dressing gown sliding off his shoulders and struggles to stand up in his nappy, stumbling slightly and swaying, feeling a slight pressure on his bladder.

"Just for now, come on, we'll get you dressed and we can go to the chippy for a treat?" He smiles and turns, expecting Sherlock to follow him.

He remembers John's earlier warning and sits still, carefully tidying up the toys into the wooden box, looking over at John as he turns to leave and calling out "Wait daddy!"

He turns, "Yes baby? What is it?" John takes in Sherlock's trembling form and kneels next to him, "Hmm?"

Sherlock sniffs and closes the box, mumbling "I didn't want to get told off" he looks down and plays with his dressing gown as the pressure in his bladder builds and he squirms "Toilet" he squeaks.

John sighs and sits down properly, pulling Sherlock onto his lap and carefully rubbing his tummy in deliberate circles.

"Toilet is for big boys baby, and you're only little."

He blushes slightly and squirms, John's movements pressing slightly on his sensitive lower abdomen making him buck up slightly.

"I can be a big boy" he weakly protests as the strain increases.

"Well you haven't been in all the time I've known you Sherlock," he sighs, and increases the pressure on Sherlock's stomach,

"Come on baby, it won't be that bad. Just relax."

Sherlock pouts moodily before the realisation of his situation kicks in and he gasps at John's hand increasing pressure, squirming and whimpering slightly, trying to hold everything in along with the last of his dignity, feeling vulnerable.

John kisses his forehead lightly, whispering encouragement into his ear, "Come on Sherlock, that's a good boy, do this for daddy, it's okay baby."

He nuzzles against John's jumper for support and tries to calm himself down, focusing on his words, his soothing voice and warmth.

"Daddy" he whispers in a strained voice, tensing and blushing as he feels a small leak from his bladder and the instant relief sets him on the edge of losing control.

He moves his hand from Sherlock's stomach to his hair, running his fingers through it gently, "Shh baby, just relax, it's okay, it's what it's meant for." He feels Sherlock relax a little in his arms, "Come on, you can do it." John licks his lips nervously, worrying that perhaps this was a bad idea.

Sherlock gasps and grips John's sides as he suddenly begins to empty his bladder, blushing deeply and hiding his face against his shoulder, trying to ignore the slight hardness that grew from the overwhelming relief yet vulnerability that came with filling his nappy. The padding swells and he hopes that it can carry it all without leaking.

John holds Sherlock close, rubbing his back until he starts to pull away. He rests his hand under Sherlock's chin and tilts it upward, so he has to look into John's eyes;

"I'm so proud of you baby, well done, that must have been hard."

Sherlock nods and sniffs, blinking in a daze and getting used to the feeling of his wet nappy, feeling sated and sucking his thumb gently, still looking at John in a fascinated adoring manner.

"Right, well, come on then." He picks Sherlock up and carries him to the bedroom, laying him down on the towel that's still there from earlier, "After this we'll get you dressed and go get some chips, how does that sound?"

Sherlock smiles weakly, watching him and taking in the concentrated yet caring look in his eyes, reaching out to gently hold and squeeze his hand. "Yes please"

He smiles back and takes the wet nappy off of Sherlock, putting it in a bag and into a bin before wiping him clean and applying talcum powder again. He rubs it in gently, humming to himself before putting a new nappy on Sherlock and securing it, "There, good as new!" As Sherlock stands John pats his bum playfully, "Now pick out what you want to wear?"

Sherlock sways slightly and totters towards the wardrobe, the idea of a suit or his usual formal wear suddenly seeming strange. "I want...one of your jumpers" he eventually requests "And some bigger trousers" he turns to him and smiles weakly.

John collects the clothes for him, one of his longer, warmer jumpers and the trousers he had bought especially, then helps him wiggle into them. He smiles and takes Sherlock to the mirror to show him -

"Don't you look cute? Hmm?"

Sherlock bites his lip and holds onto John's hand, feeling reliable on him and safe with him, shyly squeezing his hand and gently pressing an innocent kiss to his cheek, blushing and smiling happily at him.

John smiles back.