John was exhausted. His shift at the clinic had gone horribly. He, in fact, would rather go back to Afghanistan than ever return to the clinic during flu season.
He stopped by Tesco on his way home to pick up milk and tea. While there, he splurged and got himself a jar of Frank Cooper's marmalade, since he was off work for the next few days. He would have a bit of a lie in and then enjoy a cuppa and toast. It would put right this horrible day. Down one aisle, he saw a display of honey sticks in several different flavors and decided that he would get them as a treat for his favorite detective. He picked several of the little bags of sticks and went to do battle with the chip and pin machine.
As he walked from Tesco to Baker Street, his mood shifted from Doctor Watson to regular old John Watson. His mind drifted. They could get Indian take-away for dinner. A nice curry sounded lovely, and perhaps he could get Sherlock to eat some. He unlocked the front door and climbed the steps to their flat. Sherlock was home; he could hear the man muttering to himself. He pushed open the unlocked door and walked inside.
"Sherlock, I got you a surprise — What the hell is that?" John almost dropped the bags he was holding. He stared at a large chalkboard covered in what appeared to be secondary level maths.
"It's a blackboard, John." Sherlock walked around it. He watched John out of the corner of his eyes.
"Why is it here?" John sat the bags on the kitchen table; the marmalade jar clanked solidly protesting its rough treatment. John ignored it. He strode over to look at the markings that covered the blackboard. Sherlock observed how John's face lit with exasperation and intense concentration. How his eyes danced over the blackboard taking in every detail. John's mouth was a thin line, he licked his lips and bent forward to look closer. Sherlock noticed how serious John looked and went back to looking at the blackboard as well.
"It's from that case I went on yesterday with Lestrade. The murdered secondary maths teacher." Sherlock broke away from his contemplation of the equations to check out what John had brought him from the shop.
"You must've had a rough day, John. Oh, you picked me up flavored honey sticks!" He opened a bag of strawberry flavored honey sticks as he watched his blogger standing in front of the board.
John pulled off his jacket and let it drop to the floor. John never did that; Sherlock made a note of it. His breath was steady but louder than usual. Sherlock sidled closer to him. John swayed slightly back and forth on the balls of his feet. Keeping a cadence all in his hips and Sherlock found himself watching the way John's arse looked as he did it. Utterly forgotten were the honey sticks – more so the dead maths teacher.
John licked the tip of his finger and started to write the solutions to the equations in the chalk dust on the board. He worked fast, doing the calculations in his head and filled in the answers. Sherlock controlled his face to hide his delight at each correctly completed equation. His John was always an intriguing puzzle.
As John worked, his breathing sped up. He squared his shoulders back as he finished the last one, looked over the whole of the blackboard, and sighed loudly. There was a small smile on his lips; his eyes seemed deeper blue than usual. It startled Sherlock, made him want to grab John's face and memorize the color of his eyes when they looked like this.
"Um, sorry Sherlock, I couldn't help it. I didn't mess up evidence, I hope." He shrugged his shoulders and refused to meet Sherlock's eyes. "I'll be right back." The blond man dashed up to his room and slammed the door.
Sherlock
Sherlock just stood there, holding a few honey sticks, wondering what the hell had just happened. He studied the board again. The answers were all correct. John had done it all in his head. They weren't incredibly hard, but still, Sherlock was completely surprised John had done those problems so swiftly and without the help of at least scratch paper. Peering closer, he traced the answers with his fingertip lightly. John had licked his fingertip to leave those marks. That was both odd to the detective and arousing.
He had obviously figured equations like this before; it was second nature to him. John knew to wet his fingertip to leave the answers without using chalk. It felt intimate to Sherlock. And clearly to John as well. He had been incredibly turned on by the whole incident and, Sherlock deduced, had run upstairs to masturbate. It was so clear, John's elevated breathing, his dilated pupils, the light sheen of sweat that had covered the doctor's brow. John's body language as he solved the calculations, the detective had noticed the flush of pink that tinged the doctor's face and even his embarrassment as he ran up to his room. Sherlock formed a hypothesis: John Watson had a maths kink.
It would be an interesting experiment; prove his flatmate had a maths kink, and to what extent of a kink it was.
John was always surprising him in such wonderful ways.
Sherlock sat on the couch, popped a honey stick into his mouth, and let the honey ooze onto his tongue. He waited for John to come back downstairs. Sherlock made a new room in his mind palace for all the data he would be collecting. He would have to buy a blackboard for the flat, he decided. Yes, he would need one that he could fill with all kinds of wonderful equations for his blogger.
The blackboard went back to NSY. Sherlock purchased a new slightly larger one that flipped over. One side was for chalk, and the other was a white board that used markers. It was on wheels for ease of movement. He filled both sides with problems that were marginally more difficult than the ones that had been on the maths teacher's board. Then he left the package of chalk and dry erase markers out for John to find when he came downstairs to get ready to go to work.
Sherlock knew he'd be up soon to go to the clinic. When Lestrade sent him a text, he left without making a sound. He felt conflicting emotions, both relief, and disappointment. He wanted to see John's expression for his data collection, but at the same time, he didn't want John to see his expressions.
The case was a three, hardly worth it the effort.
When he came home several hours later, his eyes went immediately to the blackboard. John had answered every question, on both sides. The chalk and marker lay side by side on the kitchen table. Nothing else was out of place. All of the answers were correct.
Sherlock threw himself onto the couch, searching his mind palace for harder equations.
The experiment continued for weeks. Sherlock never saw him completing the problems. He would fill the boards with equations and leave. John would answer them when he was alone. There were a few times when they had a case and came home to the board filled with problems, but John would never solve them like he did the first night with Sherlock in the room.
Sherlock would make a point to get dinner and leave John alone with the board. When he returned, the equations would be solved, and John would be either quietly sitting in his usual spot reading or he'd be upstairs and would come down when Sherlock called him to dinner. Sherlock noted all the signs that John had masturbated after completing his task. His complexion rosy, his clothing straightened but rumpled sometimes. After a set of difficult problems, he noted that John in his haste had re-buttoned his shirt incorrectly, and the box of tissues in a different spot. Sherlock deduced that John's usual masturbation habits increased on the days there were new problems to solve. Sherlock also noticed that John was more relaxed than usual afterward.
One night, after a particularly horrible case, they came home exhausted. While the murderer was in custody, they hadn't been able to save his final victim. John had done everything he could, but the young lady had slipped through his fingers.
They both had little to say. John nodded his goodnight and went upstairs.
The board sat cleaned. That had become part of their ritual.
After John had known Sherlock had seen his work, he would clean the board, so both sides were pristine. When Sherlock went to bed that night, he found a piece of chalk on his pillow. He smiled briefly. It was time for much more advanced problems. He wanted to see how the complexity of the problems would affect John's mood. The next night when John went upstairs to bed, Sherlock slipped back into the sitting room. He wrote in the darkness the light from the streetlights illuminating enough for him to see. The sound of the chalk sliding over the board comforting. He remembered 'The Continuum Hypothesis' from his time at Oxford because of its simplistic beauty and it exactly as he'd seen it on the board then. He knew the answer; it was part of 'Hilbert's Problems.' Would John know it?
When it was perfect, he left the chalk on the coffee table and returned to his room, making sure he slammed the door so John would hear it. Then, quickly Sherlock quietly opened it a crack so he could watch John.
He waited there, listening. A few minutes later, John came down his stairs, Sherlock knew he came to check the board. He didn't turn on a light, but Sherlock could see him clearly, silhouetted by the outside light as he stood in front of the chalkboard. There his flatmate stood, wearing a faded Fraser's Chorus band t-shirt and dark pants. Sherlock could not make out the color in the dim light; he exhaled quietly, he built a room in his mind palace for how those pants accentuated John's muscular thighs. John swayed, holding the chalk in his hand. How extraordinary he looked. His hair was almost silver in the light coming in from the windows, the chalk in his hand so white.
Sherlock's erection pressed against the fabric of his pajama bottoms, the intensity of his arousal surprised the detective. He heard the hiss that escaped John. The blond man was frustrated; this problem isn't as easy as any of the others, not by a long shot.
"Oh, god yes, Sherlock. Yes."
John's whisper was the most erotic thing Sherlock had ever heard in his life, something he wanted to hear next to his ear as he pushed himself into John's body. It sounded like heat, lust, and sex. The hair on his neck prickled and he shivered, his erection throbbing at the thought. Sherlock debated if he should start collecting data to see if he had a maths kink as well. He dismissed this; he had a John Watson kink.
John turned, grabbed the marker off the coffee table, and flipped the board over. He had to go back to fix errors more than once, grunting with frustration. Each time he got closer to the answer, there was a wave of some feeling that Sherlock could almost touch. Like the excitement, they shared after a good foot chase. It was tense and hot, and Sherlock wanted to throw open the door of his room and stride over to John and just take him. He wanted to taste this emotion that had overtaken the man standing at the blackboard.
John moaned loudly, flipped the board over, and wrote the answer down. He then stood still and studied it.
Sherlock saw the movement of John's arm before he heard the sound of skin on skin. Before he could stop himself, the detective had his hand in his pajama bottoms, stroking his aching erection. He watched John, shocked by his movements. John stared at the solved problem, his whole body shaking. He moaned softly. Sherlock was so close, about to come harder than he ever had in his life when he heard John's whisper.
"Oh, Sherlock..."
The small, broken sound of John's orgasm, stopped Sherlock mid stroke. He watched as John turned sharply and looked in the direction of Sherlock's bedroom door. Sherlock's instinct kicked in, and he left his spot by the door, went to his bed, and laid down, his back to the door. He made no sound. He pretended to sleep, his cock throbbing. He could feel the stickiness from his pre-ejaculate on his stomach, and his pajamas felt tight and uncomfortable.
Footsteps slowly approached his door, then turned and quickly receded across the flat and up the stairs. Before John's bedroom door closed, Sherlock pulled his pajamas pants off and wrapped his large hand around his shaft. His other hand cupped his testicles and pulled gently. Sherlock's mind replayed the sound of his name escaping John's mouth and he felt his orgasm rip through his whole body. He whole body tingled as he painted stripe after stripe of ejaculate across his chest, stroking himself through his orgasm. Sherlock's mind went so quiet he laughed softly with surprised bliss. He could not remember ever feeling so satiated before.
The next morning, Sherlock woke early and sat on the couch staring at the 'Continuum Hypothesis' that was on the board. He remembered the professor talking about how 'one can deduce from it the values of cardinal exponentiation in all cases.' To Sherlock, this was more romantic than any love poem, the one-to-one correspondence between elements of the two sets. He realized he was writing John love poems, and John was finishing them for him, and giving them back to him. The realization made his chest tighten. He pulled out a sheet of his best writing paper and tore it in half. With his favorite writing pen, he wrote: {banana, pear, apple} and beneath that {yellow, green, red}. He thought about it a moment, then folded the note and wrote {John} and beside that {Sherlock}.
They were, in his opinion, perfectly paired off. John would see this and understand. Sherlock went to John's jacket and slipped the missive into the pocket. Isn't that what a lover would do? Hide a small note of affection for their romantic interest…
He went into the kitchen and started the kettle.
An hour later Sherlock could hear John moving around upstairs in his room. The bell rang, and Sherlock knew it was Lestrade, the detective always pressed the bell twice in quick succession. He held a groan back when he saw that Lestrade had Sally Donovan in tow. Seeing her, this early was enough to sour his stomach for the rest of the day.
"Tea?" Sherlock took down a single mug. He knew Sally would refuse. Probably for the best. He had a moldy mug that would be perfect for her and he'd happily sacrifice the experiment.
"That would be lovely, Sherlock," Lestrade said. Sally just shot an ugly look in his direction.
John came downstairs then.
"Morning." He glanced at the blackboard as he went into the kitchen. "Tea?" He spoke softly against Sherlock's shoulder. The detective pushed John's favorite mug toward him; tea made exactly how John liked it.
"Ta, Lock." He said it quietly, for Sherlock's ears only.
"What is this, freak?" Sally stood at the blackboard. Sherlock heard the small huff that John made. He could feel the tension coming from his flatmate.
"So, what can I do for you Lestrade?" Sherlock handed him his tea. Lestrade looked at the blackboard as he told them about the case. Sherlock focused on Lestrade, but he watched John out of the corner of his eye. John sipped his tea, but something in his gaze wasn't his usual calm self. He watched Sally with narrowed eyes.
"Sounds dull." Sherlock would do it, but wasn't going to pretend it was interesting.
"Don't touch that board again, Donovan." Captain John Watson's voice came from the kitchen. He hadn't yelled, but he wasn't quiet either. He was commanding. Sherlock glanced at Sally. She had been idly running her finger along the board, purposely messing up the equation.
"Oh, so this is your thing, Watson? I figured this was some formula for drugs or something that freak was working on. Maybe a poison that kills without leaving a trace." She made a face at Sherlock. Lestrade looked uncomfortable, and Sherlock glared at her.
John paced closer to the board, holding a fresh piece of chalk.
He carefully fixed the parts that Sally had messed up.
"No, DS Donovan, it's actually a hypothesis. I understand that you can't handle math beyond the subtraction of Anderson's clothes and the addition of your mouth to his prick. Don't come into my flat and mess with things that you obviously couldn't comprehend, even if I wrote the instructions ON Anderson's prick. I mean, you see that more than anything else, yeah? And stop calling Sherlock Holmes a freak or so help me, I will complain to every person who is your superior starting with Lestrade. Are we clear?" He glared at Sally and nodded to Greg. "I'm going to get ready for work now. Good day to you both." He marched up the stairs to his room and slammed the door.
"What is his problem? Did you two have a domestic last night?" She curled her lip at Sherlock.
"Leave it Sally. Just leave it." Lestrade raised an eyebrow at Sherlock. Sherlock shrugged.
Sally shook her head and walked out of the flat.
"What's up with the board Sherlock?" Greg asked quietly.
"It's just his thing. We don't talk about it." It was the truth. Well, most of it. How could Sherlock tell Lestrade he thought maybe the doctor, and he were writing love letters to each other with cardinal numbers and standard form?
"I'll see you at the scene in a bit?" Greg gazed at the board, obviously trying to work out the mystery of it.
"Yeah, I'll get dressed and meet you there. I'll probably be alone." His eyes drifted up to where John was no doubt changing for work.
Greg nodded and left.
Sherlock stared at the blackboard and wondered if the spell was broken. He felt a flash of anger towards Sally. She could torment him with her silly names, but she had upset his John.
Was he embarrassed, or was it something else? Looking at the equations on the board, and knowing about the note waiting for the doctor in his coat made him feel very vulnerable. It was a scary feeling. It was sentiment. After everything they had been through together, the fall and John's divorce — was this the right time for this?
John
John came downstairs and found the flat empty. He was dressed and ready to go, but he didn't want to leave. He wanted the morning back, only without Lestrade and that hateful bitch Donovan. He hated to lose his temper. It made him feel more like his father than he cared for.
To calm himself, he cleaned the board. He didn't like the sight of it anymore. It wasn't perfect like it had been last night. He knew that Sherlock had seen his solutions, anyway.
John couldn't explain why he was the way he was. It was just something he'd always enjoyed.
He would get a thrill when he finished his maths homework. He excelled at it and had loved the praise it earned him. When he'd decided to be a doctor, one of his advanced maths professors tried to get him to change his mind. He had stopped taking those classes in favor of the ones he needed. He had missed it, but he set that aside. Now, the obsession was back.
John sighed. He pushed the board into Sherlock's room. He didn't want to look at it at the moment. It was too much; it meant too much. He had been in love with his flatmate for so long. And now, with the addition of this… whatever it was they were doing, this had become more intimate than any relationship he had ever had with anyone else. It was just another layer to their already complicated friendship. He kept his mouth shut because he was afraid addressing it would push Sherlock away. Sherlock would always be married to 'The Work'. He probably had no interest in a wounded soldier with a weird maths kink.
Just as John was finishing up another long day at the clinic, nothing but minor colds and a few nervous new moms. Sarah had already left. It was just John and the new receptionist, who was supposed to have locked the door. John was in his office when the front door banged open. He had just gotten his coat on and begun packing up his stuff. John listened carefully, years of following Sherlock into danger had made him mindful of his environment at all times. He would go out there when he was finished sorting his office to help the meek receptionist Lori.
He heard the gunfire. With instincts born in combat both in Afghanistan and the back alleys of London, he ducked down and grabbed his phone from his pocket.
Send police to the clinic. gunshots.
He hit send and hoped Sherlock would hurry. He needed to make sure Lori was okay. He stood just as they kicked in his office door.
Sherlock
The first thing Sherlock noticed when he got home was that the blackboard was in his room, and it was clean. He felt a tendril of distress. Usually, John cleaned the board, but he never stored it in Sherlock's room. Their ritual had changed. Sherlock stood, still wearing his coat and scarf, his mind pondering what to expect when John returned home.
He hadn't spoken to John since he'd left that morning. He'd been eagerly waiting for John to get his note and text him.
His phone chimed, and he pulled it from his pocket once again. When he read the words, his stomach dropped. He dialed Mycroft as he raced from the flat.
Later, when he thought back on that day, he would remember that it started to rain. He felt each icy cold drop as it snaked beneath the collar of his overcoat when he jumped out of the cab, threw bills at the driver, and ran towards the ambulance lights. They washed the front of the clinic and the rain-drenched streets in a bloody red light.
He saw the new receptionist first, sitting on the edge of the nearest ambulance, wrapped in an orange blanket. Her face twisted with guilt as she glanced up at him. Paramedics loaded a sheet-covered body into the back of another. Deductions screamed inside his head, and he kept moving forward.
Something inside Sherlock's chest broke. His brain tried to tell him to remain calm, but his heart, that foolish, impossible organ, screamed that his John was on that gurney. Hot tears mixed with cold raindrops on his cheeks. They were so close to finally figuring it out.
Sherlock would not survive this. He remembered the anguish in John's voice as he stood on the roof of Bart's. He felt that same scared anger as he watched the body being loaded it into the ambulance. The dead body of John. His John.
"Sherlock wait!" Lestrade attempted to push through the crowd and reach Sherlock's side. Sherlock ignored him; he strode towards the ambulance, elbowing bystanders roughly out of his way.
He wanted to climb next to John's body. He wanted to hold him until the warmth of his skin was cool, and then he would follow him. They would be buried together. Sherlock was sure his tombstone was still standing in that little cemetery, the one where John Watson had begged him not to be dead. John had wanted a miracle then, and now Sherlock would give anything he possessed for the same.
This time, there was no trick, no sleight of hand that would bring John back to life.
"Sherlock! No!"
This time, the words were Mycroft's as he grabbed Sherlock's shoulder and pulled him away.
"My, I can't. I can't stand this." He was weeping openly now, and he didn't care who saw. His magnificent brain was opening every door that belonged to John Watson and Sherlock was losing control of the flow of images that moved inside his mind. It was beautiful chaos, and it would tear apart everything that Sherlock built to protect himself.
"That's not John! Listen to me, Bee, that's not John." Bee? Mycroft hadn't used that name in over thirty years. And then the rest of his brother's words penetrated. Mycroft was usually hard to read, but through his tears, Sherlock saw his brother's open expression and knew he spoke the truth. His heart rejoiced cautiously. Mycroft's words echoed through his mind palace, calming the riot of thoughts.
"Where?" He couldn't say more.
"Your doctor probably could've invaded Afghanistan without any other help. He is stupidly brave. Or perhaps just stupid. He wrestled a gun away and shot that one. They were going to assault Ms. Williams. He became wounded in the struggle, but not badly; they already took him to Bart's. Come, brother mine. I'll take you to your goldfish."
His brother's warm arm wrapped around him, pulling him towards a black car.
"He's not a goldfish," Sherlock said softly. Mycroft's lips tipped up just barely.
"No," he said, "He isn't."
Mycroft walked his brother into the hospital and deposited him in an austere waiting room. When Mycroft returned, his face was pale. Sherlock's stomach dropped.
"He's alive. He's in surgery. He left this for you." Mycroft handed him a small plastic evidence bag. Inside was a sheet of paper. Sherlock recognized his love letter, stained crimson. One section was clean of gore and John had scrawled a note in return. Sherlock could see the whirls of John's fingerprint, pressed onto the paper in blood.
9x-7i 3(3x-7u)
That was it. Sherlock looked up at his brother and smiled.
Mycroft
Mycroft had figured out the solution before he handed the paper to his little brother but couldn't figure out why i 3u had dried up Sherlock's tears. Was it a clue to a case they were working? Leaving his sibling to his illogical responses, he wrote the whole thing out on another piece of paper and asked Anthea to look it up. When she saw it, she just smiled. Her fingers moved swiftly over her phone.
"Boss, it means this." She held up her phone to show him the screen. I less than 3 u, in a text message, was I *heart* u. John had left Sherlock a message, but it wasn't a crucial hint to an unsolved crime, merely to John's heart.
The doctor came out then and notified them that John was fine. He was already in a room. The bullet pierced through his right bicep, but there was very little damage. Mycroft followed his brother and watched as Sherlock lowered the bed rail and laid his head on the unconscious man's good arm. He held his hand and whispered something that sounded a lot like theorems. Mycroft decided he didn't want to know. He left the two together, stepping outside and nearly running into Gregory in the waiting room.
"So, is it me, or is John Watson a bloody hedgehog of doom? That guy is scary. I thought you and your brother were scary, but I saw the two guys who lived. They aren't going to be breaking into clinics to steal drugs or hurt anyone anytime soon." Lestrade toasted the notion with his cup of weak coffee.
"He's perfect for my brother. Apparently, he left him a mathematical love note. Quite clever really, for Doctor Watson. Now, I want to go home, have a nice neat scotch, and take a bath with you. I'm not negotiating. I will have you fired if you don't come home immediately." Mycroft pulled the silver-haired DI along with him toward the door.
"Mathematical love note? Ohhh…. I get it now. Yes, let's go home, Myc, and have a bath. I'll even turn my phone off."
Mycroft gave him a small smile. He nodded to Anthea, leaving her to watch over his brother and John.
John
By the morning, the nurses and staff were half afraid of John and half annoyed with Sherlock and completely thrilled to see the backside of them both. Mycroft sent a car, and they took it thankfully. Neither man spoke on the way. Sherlock looked distant, and John still felt the pull of the strong pain medications he was still taking. Sherlock helped John up the first flight of stairs into the flat and then lead him to his room.
"Sherlock, I can make it up to my room. You don't need to fuss over me." Honestly, John didn't want to go back up to his room. He wanted to curl up and surround himself with the sight and scent of Sherlock. He glanced back and saw that Sherlock had already left the room. He was talking to himself.
John could count on both hands the times he'd been in this room. This was the first time since Sherlock had been back. The last time, he had written Sherlock a long letter and left it here, hidden. His therapist had suggested it. John started to laugh.
"What is it, John?" Sherlock's voice was soft. He held a pair of John's pajama pants and a t-shirt.
"Nothing, I just remembered something. I don't need to stay here Sherlock; I'm fine." He turned to look at his flatmate. Sherlock looked so uncertain and lost, unable to stay still. He shifted from foot to foot. He looked younger; his face, sheltered behind the mask of aloofness that John now knew was fake.
"Don't be absurd. Of course, you're staying in here." Sherlock pulled the little plastic bag from his pocket. The bloody note had begun to darken from scarlet to brown.
"You got it?" John smiled.
"Obviously." The tall man smiled back.
"Now what?" John watched him carefully. It was one thing to tell someone you loved them; it was another to say you were in love with them.
"Now we get you ready for bed. You need pain medication and sleep. I'll help you. I'm going to get you some water." He turned and left the room.
John walked over to the small bookshelf in the corner of the room. Each volume was lined up perfectly, as they had been that day. The dust even looked the same.
"Looking for some light reading, John?" Sherlock was back, standing close. The man was a bloody ninja.
"I'm looking for this book." He pulled it out and handed it to Sherlock. It was 'The Sceptical Chymist.'
"Surprising as always, John. Do you also love chemistry?" He held the book with the tips of his fingers and smiled slightly.
"No, open it." John took a steadying breath and moved back toward the bed and his pajamas.
"You left me a note? When?" Sherlock's voice was soft and low, and it warmed John from the base of his spine.
"I left it the day I moved out of here. It was everything I couldn't say to you because you were gone." He unbuttoned the shirt he had worn home.
"Why this book?" Sherlock took the note and put the book back where it belonged.
"Chymico-Physical Doubts & Paradoxes.' It felt fitting at the time." He had half his shirt off when Sherlock put the note down and helped him draw it the rest of the way down. Between the two of them, he managed to get on a clean t-shirt. John wanted a shower, but he was in pain and wanted sleep more.
"Do you still have doubts?" Sherlock knelt down and pulled off John's shoes and socks, and then his trousers. He helped him into his pajama bottoms.
"Did you figure out my answer to your note?" John smiled, but he felt a small twinge of fear that Sherlock would explain to him again that he was married to his work and that sentiment had no place in their relationship.
"Why maths, John?" Sherlock gave him two pills and the glass of water.
"When I was a kid, I never knew what I was going to go home to. Sometimes my parents would be happy and sometimes they wouldn't. They would fight about stupid things, and I never knew… In school, it was different. Maths were always constant. No matter how awful life was, no matter the mood when I got home, 2+2 would always equal 4."
He took the pills and water and was quiet for a moment.
"As I got older, I don't know, it just changed. I had this teacher, and he was great, constantly giving me problems and praising how smart I was. It was the year my dad left, and it felt good to hear that I mattered. Then, in college, I found myself challenged and when I solved it, I got this rush. It was… arousing. It's not something I have ever shared with anyone." He laughed softly, feeling a blush warm his cheeks.
Sherlock looked at him; his eyebrows raised questioningly, and John tried to explain.
"Sherlock, it's not something you tell a date. 'Do you want to finish this drink and go back to your place so I can write algebra all over your body with a biro?'" John climbed onto Sherlock's bed and laid down. His arm was killing him, and he wanted to sleep. He didn't like how absolutely silent Sherlock was.
"I think a marker would be better. One of those washable ones. Unless you wanted to leave it longer, so others could see." Sherlock pulled the covers up over John and picked up his letter. "Do you want me to read this?" His voice sounded slightly sad.
"It's yours. Do you understand about the maths? It's just a small kink, but I meant what I said. I love you, Sherlock. I want you. I'm too tired to show you right now and if we keep dancing around it with hints and near misses we might miss out completely." John waited for the other man to speak. He watched as Sherlock stood at the foot of the bed, his back to him.
"It will always add up to this John, know that you are meant to be mine. I've been yours for so long. I just didn't know how to say it. Of course, you surprised me by changing the language from one that I had no words for to one that I did."
Sherlock undressed slowly. He wasn't embarrassed or shy any longer. He disrobed as if they had been sharing a room for the last five years and not the last five minutes. He wore nothing but his black silk pants when he climbed into bed.
"I'm glad you're finally in my bed. I'm sorry we're too tired to explore it." He traced a pattern on John's right hand. John's whole body relaxed, melting into the bed, filled with a sense of peace. After a minute of the trickling touches, he realized that Sherlock was tracing the numbers of Pi onto the palm of his hand.
"I consider what you're doing as foreplay. Just warning you." John yawned and settled into the bed more.
"I can do this all night, John. I have the numbers in my mind palace." His tracing was exact and gently rhythmic.
"That feels lovely, Lock." John was slipping into sleep. He wanted to remember this forever. He opened his eyes to watch for another moment, but he was fading fast.
"Go to sleep John. I'll be here when you wake up." Sherlock leaned over and kissed the palm of John's hand.
John woke up a few hours later, still groggy. Sherlock was asleep next to him, his fingertip still in the palm of John's hand. He had fallen asleep mid-trace. John shifted and took the other man's hand into his. He pulled it to him to place a kiss on it. Sherlock shifted and laid his head on John's left shoulder, muttering something that sounded like 'convex body K in n-dimensional Euclidean space…' and then he sighed peacefully.
John kissed him softly on the mouth. He'd finally begun to slide back into sleep when his brain caught up with the other man's sleep-mushed words. Sherlock was repeating the 'John ellipsoid' theorem. He smiled and drifted off.