"John."

"Mmm?" John paused in his shaving ritual. It never did to have sharp objects close to his own throat when Sherlock was hovering in the doorway to the bath like that. "What?"

"You've written love letters," Sherlock asserted.

"Not since secondary school," said John. "But yes." Sherlock did not seem about to gesticulate wildly or announce that armed assassins were, at this moment, about to climb in through the bathroom window, so John drew another stripe through the foam. Sherlock, in the mirror, stood in the doorway with a thoughtful and expectant air, tapping his lip with his forefinger.

Finally, Sherlock came up with, "I require your assistance."

John ran his fingertips over his jaw. "On what?"

"A love letter, of course."

John tapped his razor against the edge of the sink and rinsed it. "This for a case?"

"No."

John met Sherlock's eyes in the mirror. Sherlock looked bemused. "It's not for a case?" Sherlock gave John the look that meant You heard me perfectly well the first time; don't be dim. John deposited his razor in its cup. "So this is for you, then. You. . . want me to help you write a love letter."

Sherlock rolled his eyes. "Very good, John."

"If you want my help, it'd do you good to be nice," John warned. He splashed some water on his face. "Why me?"

"You've done this before," Sherlock pointed out. "And it's not as if there's anyone else I can ask."

John wiped his face with a towel and tried to picture Sherlock asking Lestrade or, God help them all, Mycroft to help him compose a love letter. "All right," he allowed. "Bit. . . well, bit secondary school, though, isn't it? A love letter."

Sherlock stood up straight, shoulders back. "If you don't want to help--"

"No," John said, hastily. He hung the towel back up. "I'll help. Just--give me a moment, will you? I'd like to be dressed first."

-----

John was aware that Sherlock was, in fact, a very attractive man. Not in looks, perhaps--oh, yes, there were the cheekbones, the eyes, the raven-dark hair, blah blah blah--but Sherlock wasn't physically attractive in a conventional way, was he? His eyes were too small for such a long face, his chin too pointy, and he looked about twelve years old. What made him so magnetic was the masterful way in which he held himself and the way he looked at you, like he stripped you bare to read all the secrets between your pores. Maybe the eyes or the cheekbones compelled the first glance, but his voice, his charismatic disdain, was what compelled the second one.

But John had had enough of lost causes in Afghanistan. Sherlock had told him no, that very first dinner together, and John hadn't even been properly chatting him up at the time. So John kept it to himself, didn't look at Sherlock too hard or too long, flirted with baristas and grocery cashiers, and took comfort in the knowledge that, well, at least it wasn't because he was too old, too poor, too ugly, or had a poor personality. Sherlock simply wasn't interested in anyone. And if John couldn't have him, at least Sherlock wasn't going anywhere with anyone else.

It looked like he'd been wrong about that, but there was nothing for it now.

-----

"All right." John sat himself at the kitchen table with toast and a mug of tea. Across from him, Sherlock tapped his pen against a pad of paper. "What do you want to know?"

"Everything." Tap tap tap. "I have no experience in this area. I've looked at online guides, but they are all much the same. I much prefer hands-on data, as you know."

"Right, then." John sipped his tea. It'd been a long time since he'd written a love letter. He was pretty sure the ones he'd written in the past were all stupid and long since relegated to rubbish piles. He wondered if he'd do any better now. "Well, I don't really know what to tell you. They're actually pretty straightforward things, love letters. You just tell them why you love them."

Sherlock made a frustrated noise. "But how? Surely I can't just make a bulleted list, although that would be the most efficient and legible method," he finished in a sulky mutter.

John hid his smile in his mug of tea; Sherlock could be surprisingly sensitive to any perceived mockery. "Well, you can, if you think the other person will like it."

Sherlock brightened. "So I should present the letter in a manner that I think is pleasing to the other person."

"Well. . . yes," John said. Good grief. Whoever this person was, he hoped they were patient. "If you think they'd like a poem, then write a poem. If you think they'd like a numbered list, then write a numbered list."

"I see." Sherlock scribbled this down on his pad. John took a bite of his toast and reflected that if he were going to write a love letter to Sherlock, he'd probably write it in binary. Or no, some kind of code. Sherlock would get a kick out of that.

Of course, he'd never write a love letter to Sherlock.

"What else?" Sherlock demanded.

John made sure his bite of toast was well-chewed before swallowing it. "Erm. Well. Be loving. Sentimental." Obviously, he didn't add, because some things were not very obvious to Sherlock. "Tell them why you love them, how much you think about them. The moment you fell in love with them, if you remember it. It helps if you're a bit down on yourself, talk about how you're not worthy, that sort of thing. Flatter the other person." He caught a glimpse of Sherlock's curled lip and smiled into his cup again. "Use nice paper. And your best handwriting, of course."

"Is that all?" Sherlock asked, once he'd written it all down.

"I dunno. Like I said, it's been a long time." John took another bite of his toast, chewed, swallowed. "Do you want me to read over your letter? That'd probably be easier."

"No." Sherlock sounded positively revolted by the idea.

"All right, all right." He should have known better; Sherlock was an intensely private person, even though he behaved as though no one else had any right to it. "Well, let me know if you have any more questions." He picked up his plate of crumbs, took it to the sink, and tried not to think about who this letter was for.

-----

The bathroom door banged open--John had stopped locking it, because there simply wasn't any point--and Sherlock shouted, "John!"

John scrubbed his face with his hands. Sherlock was a haze of blue shirt through the steam. "What is it?"

"The online guides recommend a more sentimental salutation, such as 'My Dearest' or 'My Beloved,' but bearing in mind your advice, I'm really not certain how the recipient would take being addressed as my beloved."

John thought anyone who knew Sherlock, or even talked to him for more than two minutes, might find it a bit distressing. "I'd be a bit creeped, myself. I mean, do they know you at all?"

"You would? Marvelous." And Sherlock slammed the door shut again.

-----

Not certain how I am not worthy. Of course I am worthy. I am brilliant. SH

John rolled his eyes. Don't text me about personal stuff at work, he typed and sent. Then, upon reflection, he sent a second message: Just say nice things about them.

Bloody hell. John was the one who didn't deserve this.

-----

John woke with a gasp, heart hammering, searching for a gun under his pillow that wasn't there. "Stop it," came Sherlock's terse command, and John went limp. Sherlock's presence was a weight at the edge of the bed, bent over John; John's bedroom door was open, letting in a shaft of dim light.

"Jesus," John said. "I told you not to do that. One of these days I'm going to--"

"How can I be certain that my letter will be received well?"

John propped himself up on his elbows and stared in Sherlock's general direction, letting his eyes adjust. Sherlock was more wild-haired than usual, his shirt collar askew. His jaw was very tense. "How many nicotine patches have you had?"

"Answer the question," Sherlock snapped.

John sat up properly. "Give me your arm." When it seemed like Sherlock was about to be recalcitrant, John injected a bit of bark into it: "Your arm." Sherlock sulkily thrust out his arm. Sure enough, the cuff was unbuttoned, and when John rolled it up he could see the patches bright against the skin: four. He sighed and began to peel them off one by one. "There's no magic formula." At Sherlock's scathing glare, he amended, "Or scientific formula, whatever. All you can do is be sincere."

Sherlock was silent, and John tossed the nicotine patches in the general direction of the bin, not caring if he missed. He glanced at his bedside table. Christ, it was three-thirty in the morning.

"Has anyone ever written you a love letter?" Sherlock asked, suddenly.

John blinked. "One or two." He smiled fondly at the memory. Kids probably didn't do that sort of thing anymore. Probably they texted one another or wrote in each other's Facebooks, or something. "I don't know that you'd call them proper love letters. More like love notes. I like you, do you like me, that sort of thing." He rolled Sherlock's sleeve back down.

Sherlock peered searchingly at John's face. "Did you like them? The notes."

"Everyone likes getting love letters." John lay back down. "Everyone likes knowing that they're loved. It's flattering." He drew the covers back up. "I'm going back to sleep now. Don't wake me unless it's a matter of life or death."

He closed his eyes. After a few minutes, he felt Sherlock get up off the bed, and then his bedroom door shut behind him.

-----

When John came home from the surgery the next day, Sherlock was shut up in his room playing the violin, a heartwrenching melody that John had never heard before. He stood at the foot of the stairs for a moment, leaning against the wall and simply listening. Was this what it was like, then, Sherlock in love?

He closed his eyes and wondered who it was. He thought he knew everyone in Sherlock's life, although it was true he didn't accompany Sherlock on every case. Was this something he'd failed to notice, or had Sherlock been extraordinarily secretive? There was that young sergeant at the Yard, Hopkins, who obviously had a crush on Sherlock, but Sherlock looked at him like he was something stuck to his expensive Italian shoe. Was Sherlock even gay? It was difficult to say; Sherlock didn't play by any rules. Probably it was that Irene woman. There had been something captivating about her; even John had felt it, her brilliant, razor-edged mind, not so dissimilar to Sherlock's. Sherlock had her photo stashed in a drawer somewhere. But she'd gone back to America, and Sherlock would never leave London. Would he? If he did, would John go with him? Could he? Would Sherlock want him to?

The violin spiraled up and onward in a frenetic wail, and then went silent with an angry snarl. John opened his eyes and remembered to finish climbing the stairs. Well, whoever they were, they were a lucky bastard, and if they ever broke Sherlock's heart, John would throttle them with his bare hands.

-----

The next morning, John came downstairs to find an envelope propped against the kettle. The front of it said simply John Watson in dark blue ink, in what John recognised as Sherlock's handwriting.

He stopped breathing.

He simply held the envelope in his hand for long moments. It was pale lilac in colour and square in shape, with what felt like cardstock inside, stiff and heavy. Finally, with quick, mechanical movements, he filled the kettle, set it to boil, and sat down at the table to open the letter.

It said, on expensive cream-coloured cardstock,

John,

I write this letter in order to tell you that I may love you. I'm not sure, because I have never been in love before, and the feeling does not seem to be quantifiable. However, I am unaccountably fond of your smiles, even when you are not smiling at me; your jam in the fridge, even though I do not eat jam; and your jumpers, even though they are extremely unflattering. These are all signs of a great affection.

It began the moment I saw you and realised that you'd shot the cab driver. No one has ever done that for me before. Matters escalated when you were taken by the Black Lotus and I was desperate to get you back. I'd never felt that way before, and I felt that way again, when Moriarty took you. You told me to run, and I should have run, because that was the logical thing to do. But when it comes to you, it appears I cannot be logical, and worse still, I do not mind.

You have bettered my life in a thousand ways since you appeared. You stop me from putting too many holes in the walls and being too cruel. You buy milk and beans. You hoover and do the washing-up. You remind me that not everyone in the world is utterly boring and uninteresting. You are an audience for my violin. You tell me that I am brilliant, and you believe that I am capable of being a hero, even though I am manifestly not, and I find that I do not wish to disappoint you.

I would like to buy you new jumpers. I would like to compose for you a violin sonata. I would like to take you to Paris. I would even like to kiss you. And when I retire to Sussex to keep bees, I would like for you to come with me.

Very sincerely yours,

Sherlock

Sherlock set a mug of steaming tea down in front of him. John hadn't even noticed the kettle's beep.

"Do you like it?" Sherlock took the seat across from John, much as he had a week ago, when he'd taken notes on how to write a love letter. He looked very composed for someone who'd just confessed his feelings via expensive stationery, although his fingers were restless.

John swallowed and put down the letter. "Everyone likes love letters."

"Yes, but." Sherlock took a quick swallow of his own tea, surely burning himself in the process. "What about this one?"

"I like it," said John. "I like it very much." And then, "Come over here, you--you--I can't believe--" He all but dragged Sherlock over the table to kiss him, and finally they both shuffled to the side in order to avoid upsetting any chairs or cups of tea. Sherlock was an awkward, clumsy kisser, who obviously had no idea what to do with his hands, but John just kept kissing and kissing him anyway, one hand fisted in his shirt and the other bending Sherlock's head towards him. When he finally stopped, it was to say, "Why didn't you say something?"

"I did," said Sherlock, dazed and baffled, with his hair even more ruffled than usual; it was a good look on him. "I wrote you a letter and everything."

"That wasn't--" John thudded his forehead against Sherlock's collarbone and fought to keep down a hysterical giggle. "People don't normally ask the object of affection for advice on their own love letter."

"Well, there wasn't anyone else to ask." Sherlock, at least, seemed to know how to hug; his arms were very comfortable around John's shoulders. "And why shouldn't they? Surely the object of affection would know what they like."

"Christ," said John. "I thought you were writing that letter for someone else."

Sherlock sounded genuinely curious. "But who else would there be?"

John couldn't resist giggling that time, and after a moment, Sherlock joined him.