Disclaimer - I own nothing you recognise.

A Promise For Later

John sighed, rubbing a hand over his eyes tiredly. This was getting ridiculous. He watched the familiar smirk pass over Sherlock's face, the self satisfied glint in his eyes fuelling John's anger.

He threw his hands up in the air. "I give up. Clearly you're never going to let me have a normal relationship."

Shaking his head, John left the kitchen.

"John, -"

"Nope. I give up. Enough is enough, Sherlock. Just… I give up. I'm going out, I'll see you later."

Sherlock was left staring at the door, feeling a little wrongfooted. John had finally said he'd be giving up dating senseless misfits that were nowhere near good enough for him; he should be happy about that. Why then, was there a sinking feeling in his stomach that was telling him that the situation was a bit not good?

John walked the streets aimlessly, no destination in mind. Was Sherlock jealous? All the signs were there after all. Ever since his miraculous return from the dead, he'd been clingier than he ever was before, he'd made a game out of seeing how quickly he could scare away anyone who dared to look twice at John, and he seemed particularly smug every time someone assumed the two of them were together.

Was there something else? Something that John was missing? Was there a danger that Sherlock hadn't told him about, something that meant the two of them had to be together to be safer?

He didn't know. Still, without the distraction of his dates, maybe he'd be able to figure out just what was going on with his flatmate.

Sherlock glared at John's back for a moment before turning his attention back to Lestrade. Sherlock had just solved a murder inquiry in less than five minutes, but when he'd spouted his deductions, John had barely glanced his way.

"You should tell him you love him," Lestrade suggested quietly, gesturing to John with a small jerk of his chin. "Leaving him hanging like that isn't fair on either of you."

Sherlock frowned. "What are you talking about?"

"John. You've ruined all his dates for… well, since you got back. Your jealousy has been obvious for the world to see. Surely you've noticed how miserable he's been lately?"

"Wait, you think I'm in love with John? Really Lestrade, just when I was beginning to put stock in your limited intelligence! I'm not in love with him, I just can't abide the morons he's been surrounding himself with."

From the corner of his eye, Greg saw John's shoulders tense and cursed inwardly. He'd heard every word. Turning back to Sherlock, he shook his head sadly.

"You're a selfish bastard, Sherlock. I don't know why John puts up with you."

Leaving Sherlock standing alone, Greg moved to stand beside John.

"Pub?"

"I'm already there, mate," John replied grimly.

Come home. SH

I need your assistance. SH

Also, bring milk. SH

Where are you? SH

Have you been kidnapped? SH

Mycroft told me you're fine. SH

Are you coming home yet? SH

JOHN! SH

Greg blinked when the phone on the bar vibrated again, glancing up at John.

"Does he do that a lot?"

"All the time," John replied. "Especially when I'm on a date, but lately, it's just whenever I go out without him. I have to turn it off when I'm at the surgery because he texts me constantly."

"Yet… He says -"

"That he's not in love with me. Yeah. I mean, I'm kinda glad about that because as much as I love him, it's very much a familial love. I just… can't think of anything else it could be. I asked him if there was any threat he wasn't telling me about but he assured me that there isn't. Not that that means much, but…" John trailed off with a shrug.

"Maybe he was lying to me today?"

John shook his head. "Nah, if you'd been right, he'd have done that glaring thing and then shut down and got a cab. You know he believes that his body is just transport? Maybe he wants me to be the same as him? I don't know, mate, but I'm not sure how much more of this I can take."

The phone vibrated again.

John switched it off without looking at the latest text. "If he can convince Mycroft to tell him that I'm with you, your phone will start soon," he warned.

"Let's hope Mycroft keeps his trap shut then," Greg replied. "What happened with you and Mycroft anyway? You saw him quite a lot before Sherlock came back, didn't you?"

"Yeah. We met up once a week or so and then he asked me to be his doctor. I've only seen him a couple of times since Sherlock got back, but then that could be because Sherlock bitches every time Mycroft comes anywhere near Baker Street."

Greg rolled his eyes. "He's an odd duck, is Sherlock Holmes. Another pint?"

"Truer words have never been spoken. Please, mate."

John stumbled slightly as he opened the door to the flat. He rolled his eyes when he noticed Sherlock waiting for him, arms crossed and a frown on his face.

"Whatever you wanted will have to wait until tomorrow," he said, taking his jacket off and slinging it over the back of his chair. "I'm going to bed."

Not waiting for a reply, John made his way to his room, where his bed was beckoning him to sleep his horrible day away.

His head aching slightly, John dressed methodically, double checking he had everything he needed for his day. Wallet, keys and phone in his pockets, he walked downstairs.

Mycroft and Sherlock both looked up at him when he walked past but he ignored them in favour of moving into the kitchen where the kettle was waiting for him. Pouring a strong black coffee, he leant against the kitchen side. The idea of having to make small talk with the Holmes brothers was enough to make his already aching head pound.

He idly wondered what could cause such an early visit from Mycroft, but found he didn't particularly care to know. More than likely, a case had cropped up, and John was due in work in, he checked his watch, half an hour.

Draining the coffee, John put the mug in the sink before he returned to the living room to claim his jacket.

"I'm going to work. Don't burn the flat down," he said flatly, before glancing at the elder of the two. Offering a small smile, he nodded. "Mycroft."

Walking down the stairs, he heard Mycroft say, "I retract my earlier statement, brother. You're not losing him. You've already lost him."

John spent the day horribly distracted. Thankfully, his patients were all relatively simple diagnoses, and he was able to split his attention. Was Mycroft right? John didn't think so. As irritated as he was with Sherlock at the moment, he had no wish to cut him out of his life.

On the other hand, something had to give. They couldn't keep going as they were; Sherlock being desperately clingy for no discernable reason, and John so angry at times that he was in danger of saying or doing something unforgivable.

He loved Sherlock. He did. He was John's best friend, his brother in all but blood, his… platonic other half. Though the thought had passed through his mind a couple of times, he didn't want to move out, didn't want to separate their lives.

The only solution was that he would have to talk to Sherlock. Find a way to get him to open up and actually tell John what was going on. Only then would they find a way to fix things… before it ruined them completely.

When he returned home that evening, it was to find Sherlock slumped on the sofa. Stripping his coat off and hanging it up, John rounded his chair to sit down, his eyes on the other man.

"I think we need to talk," he said, his tone gentle.

"You're not leaving," Sherlock gasped out, sitting up straight, a look of panic in his eyes as he gazed desperately at John.

"I hadn't planned on it, no," John replied. "But we do need to talk. We can't go on like this, can we?"

Sherlock nodded timidly. "Okay."

John took a calming breath. "When I said that I wouldn't date anymore, I was under the impression that you were ruining my dates out of jealousy. I didn't want to hurt you. What you said to Greg yesterday; Sherlock, you can't want me not to date just because you don't want to deal with 'morons'. You could have just asked me to not fetch anyone here. I'd have accepted that."

Sherlock huffed, his fingers fiddling with the end of his shirt. John sat quietly, waiting patiently for a reply.

"It's not about the people you date," Sherlock muttered eventually. "You… you're so charming and good, John. Eventually, one of those dates is going to turn into a relationship and before I know it, you'll be getting married and moving out and… and you won't need me anymore. Things are getting back to… you're my best, my only, friend, John. I don't want you to go."

John blinked, surprised by both the honesty and the sincerity in Sherlock's words.

"Do you… d'ya want a cup of tea?"

Escaping to the kitchen for a moment, John let out a breath he hadn't realised he'd been holding. He was equal parts relieved and touched by Sherlock's little speech. Making the tea, he settled his thoughts.

Handing a cup to Sherlock, John smiled.

"I'm not going to promise that I'll never date again, Sherlock. But. 221B is home. It would take an exceptional person to make me want to leave. That said, you're my best friend. To think there would ever be a day that I don't want you in my life is a stupidity I didn't believe you capable of. Been there, done that, really not interested in repeating the experience."

Sherlock brightened. "You mean it? You're really not leaving?"

John shook his head, rolling his eyes. "If a human head in the fridge didn't chase me away, mate, your idiocy ain't going to do it."

"He seems to have levelled out," Greg commented lightly.

John nodded tiredly. "Yeah, something like that. We've addressed the issue, I'm fairly sure we're fine now."

"John? You ready?"

Patting Lestrade's arm, John offered a quiet 'See you later,' before he followed Sherlock into the waiting cab.

"Can you remember if we've got anything in the fridge?"

Sherlock shrugged. "Don't think so. I'll order Chinese when we get up. Thirty six hours is longer than you're used to staying up so you should go to bed."

John grimaced. "If I go to bed without eating, I'll be grumpy as hell when I get up. Drop me at Tesco, I'll walk from there. You go on home."

"Sure?"

"Sure."

Grabbing a couple of ready made sandwiches for himself and a pasta pot for Sherlock along with some milk for good measure, John quickly paid and left the shop.

Mycroft's car was waiting outside. Anthea, more than likely, come to deliver him to wherever Mycroft was currently situated. While the invasion would usually be greeted with enthusiasm, John was too tired for it.

The door opened as he reached it, and John was slightly surprised to find the man himself in the backseat, a wry smile on his lips.

"No offence, Mycroft, but can this wait until I'm not running on fumes?"

"Life returns to the chaotic normal, I see. You look dead on your feet, John. Anyway, I was just dropping by to invite you to dinner on Friday. What do you say?"

John nodded. "Sure. It's been a while, hasn't it?"

"My thoughts exactly. I'll contact you on Thursday with the details. And John? Do look after yourself, won't you?"

"What do you mean, you're going to dinner with Mycroft? Why on earth would you subject yourself to that kind of torture?"

John snorted, rolling his eyes.

"Not everybody hates your brother, Sherlock. We ate together fairly regularly while you were… indisposed. We became friends."

"Friends? With Mycroft? You're an oddball, John Watson."

John ruffled Sherlock's hair, amused when he got an irritable huff in reply. "I put up with you, don't I? I'll see you later."

The car was downstairs waiting for him and he climbed in, smiling his greeting to Mycroft.

"Sherlock is watching through the window," Mycroft said as the car pulled away. "You told him we were going to dinner?"

"Of course. I'm not ashamed of being your friend, Mycroft. Besides, you may be able to lie to him, but he has an inner lie detector when it comes to us mere mortals."

Mycroft chuckled. "Quite. I hear things are getting better between the two of you now?"

John nodded. "Yeah. We talked, cleared up a few points, and we're doing better now. It's a good thing. He was driving me insane."

"A particular talent of his," Mycroft agreed. "Enough of Sherlock. How are you?"

"Sir, your brother is here."

Mycroft rolled his eyes. "Send him in."

"What is this ridiculous friendship between you and John?"

Looking up from the paperwork he'd been looking over, Mycroft gestured Sherlock into a seat. When his little brother was slumped in front of his desk in his customary sulking pose, Mycroft replied.

"I don't know what you mean, little brother. John is perfectly entitled to socialise with people other than your charming self, is he not?"

"What game are you playing, Mycroft?"

"I wouldn't expect you to understand, Sherlock."

Mycroft watched through slightly narrowed eyes as the confusion on Sherlock's face cleared, an expression of wonder taking it's place.

"Oh. OH! Wait. No! Really, Mycroft?"

"If that's all?"

"John has no idea, you know?"

"I'd very much prefer to keep it that way if it's all the same, Sherlock. Now, I have work to be getting on with and you're disturbing it. I'm sure you've better things to be doing."

Sherlock left the office, catching a cab almost immediately to take him home to Baker Street. That Mycroft had more or less confirmed his 'sentiments' for John was unusual and it had left Sherlock with much to think about.

Honestly, the idea intrigued him. Mycroft and John… and odd match to be sure, but one that Sherlock was sure could be used in his own favour. After all, what better way to keep John around than him dating Sherlock's own brother?

And if it all went wrong… well, Sherlock could always keep the two of them apart. It wasn't like he didn't have enough blackmail material on Mycroft to keep him far away from Baker street.

But how to get John on board?

It was a few weeks following Sherlock's conversation with Mycroft when the solution seemed to present itself without Sherlock having to lift a finger. He was lounging on the sofa, reading through a new study while John typed up the latest case for his blog when the silence was interrupted by a quiet knock on the door.

John glanced up from his laptop but the door opened before either of them could get up. Sherlock was surprised to see Anthea, phone in hand as always, looking at John with an expectant expression on her face.

"What is it?" John asked, already standing up as he closed the laptop.

Sherlock watched on with curiosity, his study forgotten.

"Flu."

"How many days?"

"Three."

"Stubborn jackass," John muttered, shaking his head. Turning to Sherlock he added, "I'll be back in a few days, and I'll keep my mobile on in case you need me."

"You're Mycroft's doctor?" Sherlock asked, even as John picked up his medical bag.

John chuckled. "But obvious, no?"

As John left the flat behind Anthea, Sherlock chuckled. Mycroft, when unwell, was ridiculously clingy. It was almost guaranteed that he would admit his feelings for John over the course of the following few days without Sherlock ever having to get involved.

Pleased with the occurrence as he was, Sherlock took himself off to the kitchen to make tea. He might even get a takeaway… there was nothing like neglecting himself to put John in a terrible mood, and he wanted to keep his flatmate as happy as possible.

A grumpy John wouldn't be a loving John for Mycroft and as much as Sherlock hated to acknowledge it, his brother was very… in, when it came to the few relationships he'd had before. Sherlock thought John would thrive on such attention, but it wouldn't hurt if Sherlock could keep John happy at home too.

He'd done what he could for Mycroft within the first hour of his arrival, but John knew from past experience that someone had to be on hand to stop Mycroft trying to work while recovering. He read quietly in the lounge area of Mycroft's spacious flat, one ear listening out for any noise from the bedroom. Mycroft had been sleeping for four hours and would be about ready for his next dose of medication and perhaps something to eat.

A quiet groan was followed by laboured footsteps, and John put his book down as the bedroom door opened.

"What are you doing up?" he asked, standing up and turning to look at the shockingly pale man. "You could have just called out for me."

"I didn't know if you were still here."

John rolled his eyes, walking forwards. "As if I'd leave you to your own devices while sick? Do you need the bathroom?"

When Mycroft shook his head, John herded him back into the bedroom, fussing the blankets around him.

"Do you think you could eat? Soup, perhaps?"

"And tea?"

John smiled. "Of course. I'll go make them and I'll be back. Stay here, okay?"

Mycroft nodded tiredly and John left the room, heating up Mycroft's favourite soup that Anthea had dropped off a little while ago and steeping the tea. Setting up a tray, complete with medications and tea for himself, he returned to find Mycroft dozing again.

Smiling slightly, John set the tray on the table as quietly as he could, though the small noise still startled the man in bed. He helped Mycroft sit up before passing over the bowl and spoon and then sat down in the comfortable armchair across from the bed.

"If you're up to it later, Anthea dropped off a couple of DVD's for us to watch. She's sure you'll enjoy them."

Mycroft nodded, gesturing lazily to the desk. "There is a laptop on there that we can play them through since you won't allow me out of bed."

John snorted. "It's up to you. You can curl up on the sofa and watch them in the living room, or you can watch them in here. As long as you're not moving or working, I'll be happy."

"Where would you prefer to watch them?"

John shrugged. "I'm not bothered. Wherever you're more comfortable is fine, Mycroft."

Taking the empty bowl, John swapped it for the tea, and the tablets, making sure Mycroft took them.

"Watch them in here with me?" Mycroft decided after a moment passed.

Nodding, John smiled. "While you're finishing your tea, I'll run you a bath, and I'll change the sheets while you're in there, okay?"

"You don't have to -"

"Mycroft. I don't do this because I have to, okay? I do it because I want to. Please, just let me help you get better."

A soft smile lifted Mycroft's lips slightly. "Thank you, John."

"Anytime."

Two movies down and half way into the third movie, and John was struggling to keep his eyes open. Mycroft had fallen asleep a little way into the third movie, and his head had dropped onto John's shoulder, his skin heating John's scar comfortingly.

He was thinking about getting up, moving his tired body to the spare room when Mycroft shifted onto his side, his arm raising to rest against John's chest.

"Hmm, my John."

The words were mumbled, barely legible, but they struck John to the core. All thoughts of leaving left his mind as he gazed down in wonder at the man pressed against his side. Carefully raising his arm so as not to disturb his bedmate, John half embraced Mycroft to him, his hand resting in the soft hair.

Sleep claimed him in minutes.

Sherlock was confused. John had returned home that morning with the news that Mycroft was back to perfect health, but… nothing seemed different about his friend. Clearly nothing had happened during the few days with Mycroft, but Sherlock wasn't sure why.

Mycroft was obviously in love with John, and from the little Sherlock had observed, John wasn't against the idea of Mycroft being his… significant other. So what was the problem?

"Oh, here," John murmured, re-entering the living room and tossing an envelope to Sherlock. "Mycroft asked me to pass that on with the message, 'Sherlock, I don't say please very often, but please.'"

Sherlock rolled his eyes but opened the envelope, finding an invitation to a black tie ball for the following weekend.

"You're coming with me," Sherlock said, handing the invitation over. "You can be my plus one. I'll have the tailor come round to fit you for a tux."

"I'm not going to a black tie just because you want someone to show off to with your deductions," John replied.

"No. You're not. You're coming because you're the best handler I've ever had and you'll be able to stop me from shooting someone out of boredom or irritation."

"I'm not your handler, Sherlock."

"John."

"No."

"Please, John."

"No."

"John. Please, John. Please. Please. Pretty please."

John sighed, the familiar sigh of defeat, and Sherlock barely managed to hide his smug grin.

"Thank you, John."

"You look very handsome, Doctor Watson," Sherlock assured John as the two entered the ballroom. He wasn't even trying to blow smoke up John's ass. He really did look particularly handsome in the custom tuxedo Sherlock had arranged for him.

"Hmm. I still don't know why you insisted on me coming," John grumbled, but he accepted the champagne offered to him with a brief smile.

"I told you, John. I need you here," Sherlock replied, squeezing his wrist gently. "Besides, Mycroft seemed rather happy when I told him you would be joining me."

John's lack of reaction to that comment frustrated Sherlock. Why wasn't he blushing, or stammering, or… anything?

"Sherlock, John," Mycroft said as he approached. "Thank you both for coming."

"Mycroft," John returned with a small smile, while Sherlock just nodded. He wasn't here to socialise with his brother, he was here for John to socialise with his brother.

"I hope you're both well?"

"We're fine," John replied, glancing briefly at Sherlock. "You're looking much better."

"I have a rather fantastic doctor."

Ah! There was the slight colouring in John's cheeks that Sherlock had been waiting for. So John wasn't quite as unaffected by Mycroft as he liked to portray.

"I must go and speak with a few others, but I hope I'll see you both before you leave," Mycroft said, his eyes resting on John for a few seconds too long.

Sherlock quickly amused himself with deducting the people around them, and while he shared a few of them with John, gaining the occasional chuckle, he left the doctor to his thoughts. Sherlock couldn't help but notice that John's eyes were tracking Mycroft around the room.

Interesting.

John was in hell.

He hadn't been around Mycroft since he was unwell, and he was finding it rather difficult. After being called 'My John' by the older man, John had spent the rest of the few days on eggshells, He was sure that Mycroft had picked up on it, but nothing had been said.

Half listening to Sherlock's amusing deductions about the people around them, John wanted nothing more than to escape the stuffy room.

"I'm going to go out onto the balcony for a little while," John told Sherlock, barely noticing that he was interrupting Sherlock midstream of a deduction.

Sherlock just nodded, his eyes sparkling with amusement. John didn't even ask as he left his friends side to slip out onto the slightly windy balcony.

It was a lovely evening, the moon high and bright, shining over the river the old building backed onto. John sipped his drink slowly, letting his mind wander. The hand on the small of his back startled him slightly, but he relaxed when a familiar presence appeared beside him.

"Enjoying your evening?"

"It's… fine," John replied after a slight hesitation. "Just a little warm inside is all."

"Quite."

"It's beautiful out here though," John added, glancing up to see Mycroft watching him with a tender expression on his face.

"Yes… beautiful."

"Mycroft -"

"I think you know by now that I'm quite… infatuated with you, John. You are exquisite, so simply wonderful in everything you do, and yet still so… startlingly human. I've been unsure as to whether you reciprocate my feelings… a matter which I'm sure you understand infuriates me. No man has ever confounded me quite as much as you do, my dear."

"Mycroft… when you were unwell… you murmured 'My John', in your sleep. Is that… is that something you want?"

"Undoubtedly."

John swallowed heavily, his eyes trailing over Mycroft's face, lingering on his lips as his feelings for the man in front of him threatened to consume him whole. Clearly his emotions shone on his face, as Mycroft smiled, a genuine smile that John hoped to see again and again.

"May I kiss you, John?"

Forgoing a verbal answer, John snaked a hand around Mycroft's neck, pulling the taller man down so their lips met. It was a chaste kiss, a promise for more, a promise for later.

Unnoticed, Sherlock hovered just out of sight, watching his doctor kiss his brother with a small smile on his face. Things would progress quite well from here on out, he was certain of it.