I was writing this as a Christmas present for my friend Gemma, based on her own headcanon. I hope you'll all like it.

It's not like he had been examining him; between working full time at the surgery and chasing him down the narrow alleys of London after criminals, John Watson hardly had the time to notice. But he did – just this one time – and it seemed so obvious from then on.

It was one of the hottest days John had ever witnessed. Not hotter than the deserts of Afghanistan, obviously, but it sure put up a fair match. John and Sherlock had all of Mrs. Hudson's fans working around their flat while she was visiting her cousin in Cardiff; they opened all of the windows at all floors and when Sherlock seriously considered turning to Mycroft so he would get some air conditioning to be installed in the flat, John knew for sure this day was getting out of control. As he emptied the third water bottle for the day he simply took off his light shirt. He wasn't embarrassed; Sherlock had seen him shirtless before – when he bursts into the toilet while you're shampooing it's a little hard to stop him or try and hide. Usually it happened when a great breakthrough was made on a case and he wanted to head out as soon as possible, and he frankly couldn't care less about John's state. But John had learnt to anticipate Sherlock's unpredictability and adjusted to it.

He walked into the living room with his shirt in his hand. For a man his age, he was quite fit, as a war veteran should be. He sat down by the window and the fresh air, placing his striped shirt on the armchair to his left. He glanced at Sherlock, who was lying in a supine position on the sofa, a bag of frozen peas resting right on his face. He had used all of the ice they had for an experiment and had to improvise. He was wrapped in his blue robe and pyjamas, and was most definitely much too warm. "Still considering texting to Mycroft?" He asked him, disported.

"More and more by second." Sherlock snarled from under his bag of peas. He lifted it from over his face and exhaled dramatically, rubbing his eyes. "Bored."

"Oh, no, you're not starting again."

"Relax; I have no intention of taking the gun from where you hid it in the vase above the fridge." He smirked as he watched John trying to come up with an appropriate reply. "It's obvious."

"Alright, whatever you say." John quickly changed the subject – Sherlock has been through a week and a half without a case and was in a spiteful mood. Giving him an audience for describing how he figured out such a mild thing would be like giving a 5 year old a paintball gun. Nothing good could come out of it. "Why don't you change to something lighter? You must be melting under there."

"I'm alright." A thin layer of sweat was forming on his forehead.

"With 35 degrees Celsius and long, flannel pyjamas? Yes, I'm sure you're alright." He snatched the bag of peas away from Sherlock's hands. "Go change."

"No." Sherlock insisted. John struck him with an are-you-seriously-going-to-argue-over-that glare and Sherlock glared back. It's like dealing with a child, John thought, when another random thought crossed his mind.

"Sherlock, do you even own any short clothes?"

Sherlock didn't reply. He just curled up, facing the back of the sofa, in what John saw as sulking over his now lukewarm bag of frozen peas being held captive. John pursed his lips, trapping the words inside, threw the bag at Sherlock and headed up to his room without another word. But from that day on John noticed.

Sherlock never exposed his bare skin above the wrist line.

He started observing, not too blatantly, but attentively, and just as he thought – he didn't manage to find a single moment when Sherlock's arms weren't cloth-covered. Not on warm days, not on cool days when the heating was on. Not ever. His final confirmation was when he left his phone next to the toilet sink, and as he reached for the doorknob while Sherlock was showering inside, he was surprised to find that it was locked. John never locked the door. There was one exception – when Sherlock used one of his nicotine patches. Always the same hand, sleeve always rolled up at the same height.

He was intrigued. Of course he wasn't expecting to see Sherlock walking around half naked, but at least a shorter shirt, rolled up sleeves when washing his hands. Something. But there was none. And Sherlock was saying John wasn't observant.

But the point still stood. Sherlock revealed no skin whatsoever.

Three days before Christmas John finally discovered he wasn't mistaken. He was helping Mrs. Hudson carrying her Christmas tree into her flat, and politely avoided from helping to decorate it. He wasn't being rude, just exhausted from his shift at the surgery. He volunteered Sherlock to help her instead, making up his mind that if Sherlock doesn't do this one nice thing for Mrs. Hudson, at least on Christmas – he will confiscate his phone, and he can sulk all he wants. Their own tree was already set and prepared, and Sherlock discovered surprising willingness to help with it. Unpredictable, just as John predicted. Even if all he did was criticising John for his impreciseness and ordering him around from the sofa – at least he took part in the preparations. John still had to buy presents for his family – god knows what he could possibly buy more after 30 years of Christmas presents – and decide whether to buy Sherlock a present or not. And of course, drag Sherlock to the shopping centre to purchase a gift for Mrs. Hudson. That would be easy. John let out a sigh and wished Christmas was behind him by now. He climbed up the stairs, reached 221B and entered the flat absently.

His attention focused immediately on the figure in front of him.

Sherlock was standing by the window, shirtless. His back facing John, and he turned around almost the moment he heard the door open. But that was enough for John to take in the full image.

Sherlock's back was scarred and damaged. The cicatrices were netted across his back, entwined with each other and sprawling all the way to his arms, above the elbow joint. Shiny scars that turned Sherlock's upper body into a fascinating, defaced surface.

John's words were caught up in his mouth. He opened it to say something but closed it again almost immediately. Sherlock turned away quickly, wearing a neutral expression. He grabbed his purple shirt from the armchair's back rest and put it on stiffly, buttoning it without looking at John.

The elephant in the room was roaring and John couldn't take it. But before he could say something to break this awful silence, Sherlock preceded him. "So now you know." He said it rather indifferently, as if he was talking about the weather or their latest case. He turned on his heel, facing John again, and sat down on the sofa. Since a reply never followed he added. "You've been examining my dressing habits for the past month."

"You noticed?"

"Of course I noticed, John. You weren't exactly subtle, despite what you might think." He said that with the faintest tone of exasperation but John flinched as if he had just been scolded. He resisted the urge to lower his head and stare at the floor, and instead looked Sherlock straight in the eyes. He tried to figure out what to say – should he bring up what he just saw? Should he not? He was still slightly startled; he never expected... that.

Eventually he decided to stall. "Why were you walking around the flat with no shirt?" Oh, god, it sounded so wrong. So out of place.

"I was developing the photographs from the Clearwater murder case." He tilted his head toward the window. It was only then John noticed the pictures that had been duct taped to it. "Stop bath solution[1] was spilled over me and I had to change. I've only just put the photographs on the window when you entered. An hour earlier than expected." There was an almost unnoticeable hidden meaning in his voice in the last sentence, but John caught it.

He thought John would only be back later. And wouldn't see.

There was a minute of awkward silence and the elephant became wilder. He picked up the nerve and started. "Ho –"

"It was a long time ago."

The look in Sherlock's eyes was detached. John decided to try and go deeper. "Still?" He stepped forward and sat on the sofa next to Sherlock hesitantly, uncertain of whether the gesture or the questions were welcome. Sherlock didn't take his eyes off him, analysing his behaviour no doubt. John put on his own best neutral expression.

Eventually it was Sherlock who broke eye contact first. As hard as he tried, his distant facade was beginning to crack. Someone else probably wouldn't have noticed; but John was close enough and empathic enough to see through the cracks. He perceived the perplexity, even the slight unease the subject awoken in Sherlock. It probably hasn't been brought up in a long time. Finally, he spoke. "Child abuse wasn't always quite arousing the awareness it does today." He said quietly.

Oh.

John thought of a proper response. Everything that came to his mind sound dull and out of place in light of what he just heard. Sherlock's gaze was set straight front, eyes piercing holes into the fireplace. He didn't seem like he was going to say anything else, and they slipped into awkward silence.

"You've got questions." Sherlock said, all of the sudden.

John decided not to defend himself. It would only make him angry. "Naturally," He admitted. He lingered for a few moments, trying to decide how to take it from there. "What was it?"

"Belt. Sometimes keys for… special occasions." He said ironically and the corner of his mouth twisted upwards in half a smile. "If I was in the wrong place in the wrong time it was burning cigarettes. And of course, the usual – beat ups, verbal violence."

He spoke flatly as if talking about a different person, not himself. It put John into a slight discomfort, but he concealed it and asked again.

"And Mycroft…?"

A chill went through Sherlock's spine; John realised he had hit a nerve. Sherlock's body stiffened, however he provided an answer. "He never hit Mycroft." He said, "Good, successful, 'why-can't-you-be-more-like-your-brother' Mycroft."

He spat the words out so bitterly John couldn't stop his eyebrows from rising up. Sherlock's eyes were two pale ice cubes, smouldering in cold fire. At least, that's how John felt inside when looking at them. Sherlock never seemed to be embittered over his older brother – irritated by him, yes; hostility, of course. But no bitterness whatsoever. Sherlock even seemed quite condescending of Mycroft whenever he met him, tacitly declaring himself better. Therefore Sherlock talking so exasperatedly about Mycroft was completely out of character, and John didn't know how to react to that. Besides, Sherlock was always smug, abounding self-sufficiency. He was completely satisfied with himself. He wasn't an unhappy man; John knew that that wasn't an act. He began to question whether he knew Sherlock as well as he thought.

"That's why you're so hostile toward him?" He asked hesitatingly.

"Hardly. He just stood there. Stood there and watched me being beaten. Perhaps he was afraid, but it doesn't matter. He should have done something."

"Sibling rivalry." John said under his breath.

Sherlock was no longer frozen. He just seemed as if he was back there again, back to his childhood. Talking to John from the past. "He only stepped in when he came home one day to find me bleeding massively on the floor when I was eleven. It wasn't the first time I lost consciousness because of our father, but it was the first time he had to call an ambulance. He told our mother everything in the hospital. But it was too little, too late. He's my brother of blood, and that is it." He finished determinedly.

Mycroft and Sherlock's relationship as brothers suddenly made a whole lot more sense to John. The root of their rivalry was much deeper than John expected it to be. He could no longer blame Sherlock for the way he treated Mycroft. In the back of his mind he could also understand Mycroft for worrying about Sherlock the way he did. Child abuse could develop emotional blockage in the child and a difficulty to trust those around him – and Sherlock certainly revealed those two traits. It could easily lead to self destruction. Well, that would definitely explain his old drug habits. No wonder Mycroft had been keeping a close eye on him.

John was certain Sherlock was practically reading his mind whilst he was connecting the dots, putting it all together. He dared to question further. "Why didn't you do anything? Why didn't you tell someone?"

"I was afraid, John. The word of a child against the word of a seemingly refined adult, who do you think everyone would believe?" The tone of exasperation returned to his voice and John decided to take a step back. This was clearly a painful subject. If it were someone else Sherlock would just ignore their questions and pretend he couldn't hear them. But not John. John was a friend. Sherlock pushed through the pain and told John the truth, without filtering the details. The expression on his face shifted again; he seemed as if he was that broken kid once more, he looked so vulnerable now, and at some level this terrified John. Sherlock had never shown any kind of vulnerability. Deep down John realised he had become accustomed to the thought that there was simply nothing this man would have been vulnerable in front of. Oh, how wrong he was. To think his friend couldn't feel. But perhaps he knew he was wrong all along, and simply rejected it – because it would have damaged the halo Sherlock had established for himself in John's eyes as a column in his life.

"What did your mother do?" He asked, "After Mycroft told her?"

"She protected me – she knew the police would have wanted my statement; they would have wanted me to give my testimony. All I wanted was to get away from this man as far as I could. So she made herself the victim."

"She lied? To a judge?"

"You'd be surprised what a mother would do for her child. Mycroft was old enough by then, he played along. She divorced him and claimed full custody, and the restraining order determined that he couldn't come of more than 50 meters from us. I've never seen him again."

"And you? How were you?"

Sherlock raised his eyes to John. The look in them was surprisingly of understanding. "How do you think I was?"

Sherlock was right – John didn't need an answer.

Once again he remained speechless. He had no further questions and Sherlock had nothing else to say. Everything John could think of sounded dull, artificial and even simply dumb. Sherlock's eyes were fixed on the floor; he wore his neutral expression again. And suddenly John came up with the perfect thing to say.

"Chinese or Indian?"

Sherlock's gaze darted up to John and the faintest flash of surprise crossed it. He lingered for a moment and a smile slowly spread on his face. "Chinese, of course. Make sure they send the Sesame Chicken this time."

John smiled as well and read the things Sherlock didn't say in his eyes. Thank you.

Thank you for telling me.

[1] - You know when they develop photographs in darkrooms, and they soak the picture into some sort of liquid and then leave it to dry? Well, I meant that liquid. I looked it up and that's the best Google came up with. If there's a better way to name it, do tell.

Okay, well... I hope you enjoyed. Reviews are welcome. Gemma, I worked hard, you better appreciate that :)