Seduction, Exception

Seduction. The smoky burn of whisky lingering on Mycroft's tongue was harsh in Sherlock's mouth, dry and sensitive as it was from his unplanned nap. But he chased the edgy, bitter pleasure, the pleasing shock of Mycroft's roughness in their first unbrotherly kiss.

His right fist was tightening in Sherlock's hair, almost painfully, but he savoured the sting in his scalp. In contrast, the fingers of Mycroft's left hand traced the contours of Sherlock's right cheek, mapping by touch the bones under the flesh, refamiliarising themselves with the shifting of the muscles and skin as he kissed back hungrily.

It felt perfect, this undercurrent of brutality. He needed it, probably deserved it, after all of Mycroft's superhuman patience over his lifetime of impossible misbehaviour. After all of Mycroft's suppressed desires, and Sherlock's whimsical treatment of them as and when he chanced to remember.

He hadn't been completely honest five minutes ago when he claimed to have wanted his brother that drug-tainted night. He hadn't, if he remembered that moment correctly. He'd been prepared to go through with whatever might have induced Mycroft to give him money – a blowjob, a handjob, full-on fucking, anything – but it had just seemed like an interesting experiment at the time, with the potentially sweet reward of another hit of heroin.

But dishonest? Not entirely, either. Other moments had come back to him during these two weeks that Mycroft had gone away and ignored him. Like when he was 13, just beginning to feel the itch of his adolescent hormones upsetting his body's equilibrium. For years, he had observed his brother shedding his puppy fat, but in one startling moment he realised the sum of it – just how much of the Mycroft he'd known had disappeared. All the excess flesh had melted off his frame, exposing a 20-year-old stranger he had never seen before (physically, at least; Mycroft's gorgeous mind was the same). Sherlock felt a sense of loss because, when he traced the web between the bare patches of his memory, he knew he'd loved the Mycroft who had melted away, yet his body nagged him with annoying twitches of carnal interest in this stranger – lean, ever so tall, pale, irritatingly proper, the weight of the world on his shoulders, Atlas not yet turned to rock, Atlas refusing to shrug…

Oh, damn. Sherlock was dragged back into the present, jolted by the sensation of… cessation, actually. Mycroft had stopped kissing him, although his right hand remained fisted in his hair while his left traced Sherlock's jawline. He tried to draw him back down, but Mycroft resisted, hovering above him, penetrating him with eyes that were dark with longing, yet sternly uncompromising.

"I'd prefer it if you didn't lie to me, Sherlock," his voice, low and kiss-roughened, was otherwise inflectionless. "You didn't want it that night, and you didn't simply forget you wanted it. You never did, did you?"

A prelude to withdrawal. Was that a farewell kiss? No, he could salvage this, because Mycroft was still rock-hard against his groin under the duvet, and he was very aware that the fingers of his brother's left hand were now trailing down his neck, stroking maddeningly arousing lines over the sensitive nerves of his throat. He shivered with the sensuality of it, knowing all was not lost – if he played it very, very honestly, but also cleverly, he wouldn't lose Mycroft at this vital juncture.

It was impossible, at any rate, to lie to Mycroft right now. However well he could act, it wasn't too often that he could hide from his brother, and deception was not possible when they were like this – Sherlock naked, their bodies flush, those unnervingly familiar/familial, perceptive eyes boring into his from three inches away.

"When I was 13, I mourned you and rediscovered you all at once," Sherlock began to speak, a little breathless from the sensations of Mycroft's fingertips drawing another sinuous line down, then up, the side of his neck. "You'd burnt every last ounce of excess weight off your bones, and though we were no longer close, I missed that old body I'd adored. You looked like someone I didn't know at all, but I was fascinated by the way that stranger looked – and even more fascinated by how he looked at me. God, Mycroft, the way you looked at me…"

"You were always a beautiful child," Mycroft said, his voice a little softer, although still too grim for Sherlock to think he wasn't in danger of losing him. "But for the first time, I could see the man you would grow into, and I couldn't look away."

"When I was 14, and you were home from uni that summer, you appeared even more of a stranger, but you were still my Mycroft when I fell out of the ash tree on the south side of the cottage, and you panicked," Sherlock smiled, his breath catching as Mycroft dipped a finger into the hollow at the base of his throat. "You literally picked me up and cradled me on your lap as if I'd been six or whatever. It sent the weirdest shivers through me. So I clung to you instead of pushing you away like I'd been doing since… probably since Victor disappeared, though I'd forgotten."

"It was the last time for a long time that you clung to me," Mycroft recalled. "Until you started on the drugs and went through those periods of helplessness before you learnt to manage your comedowns better."

"I had a hard-on, you know," Sherlock admitted with a huff, cautiously stroking his thumb over the nape of Mycroft's neck. "Could barely believe how you snatching me into your arms could do that to me. I was afraid you'd feel it, but I didn't want to let go of you."

"Was that why you were squirming while wrapping your arms around my neck?" Mycroft asked, with the hint of a smile.

"You couldn't tell?" Sherlock asked, a small tremor running through him as Mycroft loosened his grip on his hair to trace soothing patterns into his scalp.

"No, I was terrified – I thought you'd landed on your head," Mycroft murmured. "I was even more certain the fall must have knocked all sense out of you when you clung to me, because you hadn't wanted to be near me for years, ever since I'd been unable to bring Victor back."

"I was angry with you," Sherlock said softly. "I shouldn't have been. You were only a child too when we lost Victor. What could you or I or anyone have done with Eurus, whose mind we still don't understand? But I couldn't remember why I was upset with you. I only knew I was. Later, when I felt what I felt for the stranger you'd become, I tried to erase my feelings. So I might not really have wanted you that night when I was 17. But it's also true that I wanted you before; I just pushed it into the gaps in my mind."

If they were to obey logic, Sherlock knew that Mycroft's next question ought to be: "Why now, then? What attracts a person at 14 is not what attracts the same person at 33, so what is this? Pity? Pity for the stuffy, ageing figure of fun you've made me out to be for years now?"

Sherlock knew that if he had to produce an answer, he could compose one that might go thus: "Because I remember now how much you loved me but held back for my sake. And I know how much you still love me and are still holding back. I ribbed you for years because I didn't want to see how much the stranger you metamorphosed into when I was 13 still intrigued me. I'm growing to like what I see, and I've always been in lust with your mind, so I want to try this."

But in truth, he didn't know if he could explain it that way, because it went beyond logic and sense and chemistry and mathematics. It was magic and instinct and alchemy and myth, and he might struggle to write a rational psychology exam answer on it even if Moriarty were to rise from the grave to hold a gun to his head.

Moments passed, yet Mycroft held back from asking the logical question. He remained silent as they lay together under the duvet, caressing Sherlock's hair and throat, and Sherlock perceived – through instinct, magic, or whatever had snatched the reins from cold reason – that what Mycroft felt was trepidation. He was afraid to pinpoint what Sherlock wanted from him now, and afraid to be either too precise or comprehensive about what he wanted from Sherlock after denying himself for so long.

Sherlock searched for something to say, but Mycroft bent to kiss him again – with unbearable gentleness this time. Had Sherlock extracted the appropriate words from the maelstrom of language in his head, he wouldn't have known how to use them now, not when Mycroft's hand was stroking a long, burning line down the side of his body to his right thigh, while his mouth explored Sherlock's tenderly.

Words became inadequate. They'd always had other languages, he and Mycroft, through the seasons of their lives as brothers, enemies, reluctant comrades-in-arms, a brace of demons battling back-to-back on the side of the angels while taking occasional casual jabs at each other. Now, they were discovering yet another language they had never used together, learning it swiftly on the fly. They'd conversed in a similar tongue with other people, but it was different with each other. It was always unique between the two of them – the lightning speed of communion, semantics no one else could fathom, a secret grammar sprung from the unholy union of devils and the Sons of God.

Mycroft eased out of the kiss, and Sherlock's throat involuntarily summoned a half-growl, half-whimper. He thrust up against his brother's belly, only to have his right hip gripped by a firm hand to hold him still. He was readying himself to whimper again in protest when Mycroft began a series of infuriatingly light kisses from one corner of his mouth down his neck to his collarbones, peppering his skin with altogether not enough strongly-worded sensation, until he flicked his tongue over Sherlock's left nipple, and Sherlock moaned, clutching at the back of Mycroft's head. Mycroft licked and mouthed at the dusky circle of skin, making it pucker and stiffen, then suddenly nipped at it. Sherlock jumped, only to be soothed by another caress of his brother's infernally clever tongue.

He was just beginning to lose himself in the sensations of the sensitive nub of nerves being drawn into that nimble mouth when Mycroft switched over to his other nipple while running a hand beneath Sherlock's hips and slipping it under his arse to pinch his right buttock.

Sherlock yelped.

"Mycr–" he whined, but Mycroft straddled his body, pushing the duvet off both of them, exposing Sherlock completely. His mouth was covered again in a searing meeting of lips, tongues, teeth – nothing tender, nothing sweet, the coppery taste of a smear of blood seeping from one or the other of their lips – it didn't matter, when they were one blood and one flesh, anyway.

In their fledgling language, Sherlock could read Mycroft, in every affectionate touch, every dominant push, communicating: Patience – be still – you needn't always tear along at such a frenetic pace – let me take you apart and think about whether I'll put you back together the same way – forgive me for almost getting you killed – I'm sorry you didn't know I was always there for you – but you were a handful, brat – no, I'm not sorry you suffered sometimes – you could have done with a thorough spanking – rascal – you have no idea how much grief you've caused me – I adore you, I adore you, I adore you…

Sherlock answered, meeting Mycroft's tongue with his own, tasting him through the tinge of blood in their mouths, daring now to let his hands roam over his brother's still-clothed back, his chest, his arms, his sides. But when he tried to tug those lawn-cotton pyjamas off him, Mycroft pushed his hands away.

He voiced a guttural complaint and tried to break the kiss so he could speak. But Mycroft put the brakes on that by running a finger down the length of his younger brother's cock, drawing a gasp from him. As Sherlock's breath caught, he locked eyes with Mycroft, and that very moment, Mycroft curled a firm hand around his shaft and stroked once, twice, three times, making him pant.

"Mycroft…" he began, a little hoarsely, but his brother seemed determined to continue their exchange in the new language they were learning instead of reverting to old speech, for he removed his hand from Sherlock's rampant, weeping erection, drawing another whine of protest from him. Before the whimper could shape itself into words, he grasped Sherlock's hips with both hands, shifted down, and dipped his head to take his cock into his mouth in one smooth, hot glide that had Sherlock yielding to him with a cry, arching his back and baring his throat.

He shifted a hand off Sherlock's hips to grasp the base of his shaft, controlling the depth of his thrusts, while his other hand caressed all the inches of skin he would never have explored when he had strictly been Sherlock's brother – the firm curves and the crevice of his arse, his scrotal sac, the insides of his lean-muscled thighs – leaving him trembling for release.

Infuriatingly, when he was close, Mycroft let him slip out of his mouth and applied firm pressure with his thumb and forefinger just below the head of his prick to slow things down. Sherlock almost howled with frustration, but Mycroft reclined smoothly beside him again, and nipped gently at his left ear with his teeth. Sherlock inhaled a shivery breath through gritted teeth, then dissolved into mush again as Mycroft teased his ear with the tip of his tongue, tracing the curves and grooves of the tender shell, telling him without words: Always in such a hurry. Slow down sometimes, when there's no need to rush.

Mycroft curled his hand around him again when he felt slightly less hard, and resumed a moderate, steady rhythm. Paired with the teasing tongue in his ear, it had Sherlock quivering with so much stimulation, he twisted his head towards Mycroft's face, both to hide his ear against the bed sheet and to look at the one who was reducing him to this state. Mycroft gazed at him with an expression that mingled pleasure and guilt, affection and steel, arousal and concern. Sherlock slid one hand over Mycroft's cheek, then his temples, then ran his fingertips over his nose and lips, trying to count every careworn line, wondering how many he himself had put there.

It was intensely intimate, this – looking into each other's eyes and exploring the mortal lines on his brother's face while he trembled and panted from the steady flexing of Mycroft's wrist. He didn't want Mycroft to look guilty, or sad, or worried; he wanted… he just wanted… but the pace dictated by that elegant, deadly hand sped up then, and Sherlock felt himself impossibly hardening and tightening even further, everything growing taut and pulling up, and surely he couldn't keep going like this without bloody losing consciousness? Then in a second, his fingers were no longer touching Mycroft's face, because his brother had shifted away after brushing a kiss against the palm of his hand – to sheathe Sherlock's prick with his mouth again, and the wetness and pressure and heat were just perfect.

His game of seduction had led him up this peak, and Mycroft had played an even better game, because Sherlock was the one now on the precipice.

He tipped over the edge.

He orgasmed hard, crying out incoherently as he emptied himself down Mycroft's throat, consumed from head to toe with sensation that whited out his vision for several seconds. Maybe his hands were crushing the sheets, or tearing his brother's hair. It hardly mattered in those moments of weightlessness, of free-fall, when everything seemed possible. Even happiness.

Exception. He swallowed when Sherlock came in his mouth, without even having to think about it, which said much about his psychology in relation to his brother. On those increasingly rare occasions when he had been the one to go down on a male partner, he had seldom permitted the ejaculate to enter his throat. The taste and texture were not to his liking, especially if the man was a smoker – something about a smoker's load was particularly sour and unpleasant. But as had been borne out repeatedly over the course of their history together, what was unacceptable from others was acceptable if it came from Sherlock.

Again, that said much about how his mind worked when it involved his little brother. And the fact that this person naked here in his bed – sated and semi-delirious with orgasm and mental fatigue – was his little brother spoke several libraries' worth of possibly highly disturbing things about them both.

"Are you all right?" Mycroft asked, lying alongside Sherlock, slipping an arm over his flat, creamy, abdomen – rising and falling as he met his body's demands for oxygen in the wake of his climax – to rest his hand in the gentle dip of his waist.

Sherlock mumbled indecipherably without opening his eyes, so Mycroft kissed his cheek, drew the duvet over him, and turned towards the edge of the bed. He had just sat up and swung his legs over the side where his bedroom slippers were when Sherlock murmured: "Where do you think you're going?"

Mycroft turned his head to see that he had opened his eyes and was watching him with a keenness that no one who had just climaxed violently, and been ready to crash from mental exhaustion two hours ago, had any right to display.

"To get some work done," Mycroft said, reaching back to squeeze Sherlock's right ankle through the duvet, in what was intended to be a reassuring "everything's fine, go to sleep" gesture.

"Why did you ignore me for two weeks?" Sherlock asked. It should have seemed like an out-of-the-blue question, but between the two of them, verbal arrows flying out of left field weren't always surprising. Or illogical.

"I thought we needed a cooling-off period – after all that… excitement at the restaurant," Mycroft said softly, but also a touch ironically.

"Does this seem cooled-off to you in any way, shape or form?" Sherlock asked with a wryness to rival his, propping himself up on his elbows.

"I wanted time and space to think. About you, this, us."

"Your conclusion?"

"That there was a high probability of my going along with what you wanted, provided it wouldn't destroy you."

"I'd say you almost destroyed me with some mind-exploding sex," Sherlock said, completely straight-faced, sitting up fully.

He didn't stay there, of course. Not Sherlock. He pushed the duvet aside, leaned over, and wrapped his arms around Mycroft's waist, hands slipping under the fine cotton. Mycroft put his hands over those exploring ones, the fabric of his pyjamas between them, tamping down the urge to flee not only because he had just shamelessly sucked his sibling off, but also because, of all the places on his body, Sherlock had to be running his hands over Mycroft's middle – less than taut and not always trim, a constant cause for self-consciousness.

"I'd hoped that mind-exploding sex would at least make you go to sleep as you ought to have done right after solving the puzzle," Mycroft sighed, failing to nudge his brother's persistent hands off him.

"Hmm, you should have tried that tactic when I was a kid and wouldn't lie down for days," Sherlock chuckled, resting his chin on Mycroft's shoulder.

Mycroft felt his cheeks burning, and he attempted to wrench himself out of his embrace, snapping: "For God's sake, Sherlock, I am not and never was a paedophile!"

Sherlock clung to him stubbornly with his ridiculously strong arms – and laughed softly: "I know, Mycroft – I know. You've never been that sort of deviant, although you're all other kinds. But so am I. And you were the best big brother. Always. I didn't know it, and I'll probably forget it again next week in some fit of insanity or temper, but you were and are the best."

"Anyone who knew you'd said that about me right after coming in my mouth would be left in no doubt about your insanity," Mycroft groaned.

Sherlock was kneeling up behind him now, arms encircling his chest as he nuzzled him, planting kisses on his temples, his ears, his cheekbones, his jaw, and the nape of his neck where the ends of his hair touched the skin. "As I said, we've always done things no one else could," he murmured in between the nuzzling and kissing. "I want you in all ways, Mycroft."

"Do you, really?" Mycroft asked. Sherlock was made of impetuousness, desire for novelty and excitement chased hard by crashing boredom and abandonment, and questionable judgement in his choice of stimulating substances. Mycroft had no wish to find his name on a grubby list in Sherlock's pocket months from now after everything had gone pear-shaped, scrawled after "cocaine", "heroin" and hell knew what else.

"Mm-hmm, really," he whispered, cupping Mycroft's chin with one hand and turning his head gently to one side so he could kiss him on the mouth.

Sherlock could probably detect the residual taste of his own semen on his tongue, mingling with the last traces of the whisky. He probably didn't care. He'd always been far less bothered than Mycroft about peculiar tastes – the mad chemist, dabbing all manner of dubious substances onto his tongue to discover what they were. Each year, on his brother's birthday, their father had always found a way to express surprise that Sherlock had survived as long as he had without metamorphosing into some manner of beast (with odds on it being one possessed of scales, horns and a forked tail).

He was pressed right up against his back now, still kneeling, but with his legs spread so his thighs and knees bracketed Mycroft's hips. His hands made their way down Mycroft's body, and he asked: "May I?"

Mycroft didn't answer, which Sherlock took as permission. It was becoming a habit. ("You haven't said no. It's a date.")

Sherlock undid the drawstring tie of Mycroft's pyjama bottoms and slipped a hand inside to curl his fingers and palm about his phallus, still hard as a rock. Mycroft drew a hissing intake of breath, and his entire body tensed – which did not go unnoticed.

"Can I undress you, Mycroft?" Sherlock asked with uncharacteristic gentleness. "I want to see you."

"There's nothing to see."

"Is it so difficult to think of yourself as an object of desire? You turn Lady Smallwood on, that's for sure."

It was miles beyond disturbing to be talking of his other lover while his brother was slowly fisting his prick, but nothing about them had ever been normal, had it?

"She was married for many years to a man with very human imperfections, both physical and emotional," Mycroft said, his breath growing slightly uneven. "She is a woman who is most forgiving of flaws, mine included."

"I like all your flaws," Sherlock whispered, stroking him from weeping head to engorged root, slowly, carefully. "They're what make you human. If I've ridiculed you in the past it was because I didn't like how you tried so comprehensively to erase them and be less human."

Mycroft was unconvinced that most of the ridicule wasn't merely regular cruelty from an insensitive younger sibling, but this was as close to an apology as he would get from Sherlock at this point. He told him frankly: "I don't believe you. But I believe that's what you want to believe, so I'll accept it for the present."

"I'll make it true from now," Sherlock responded. "Let me see you."

"No. It's fine this way."

"Can I use my mouth?"

"No, just keep going like this."

"You'll come in your pyjamas," Sherlock said, stopping the movements of his hand – explicitly against Mycroft's instructions to just keep going. Infernal brat!

"My problem, not yours," Mycroft said through gritted teeth.

"It's going to be dry and uncomfortable."

"Again: my problem, not yours."

"You don't even keep any lube in this house."

Mycroft rolled his eyes. Of course Sherlock would have done a thorough search of his home each time he broke in. "There's never been a need for me to keep lubricant in this house as I've never planned to bring a whore or a lover here." No one's ever meant enough to me for me to bring them home. And then there are little brothers, who bring themselves over…

"So where's your stash of lube, then?" Sherlock asked. "Besides your office – for those, you know, sessions with Lady Smallwood. You must have some at the club. Kinky. How many whores have you fucked over your desk at the Diogenes? And how many of them were MI6?"

"I thought you would be able tell me that based on the number of additional creases in my middle finger, or some such nonsensical guesswork," Mycroft huffed. "You know perfectly well that I don't fuck my agents. To put it in Uncle Rudy's crude terms, you don't shit where you eat."

"Lady Smallwood is a colleague."

"She and I are equals at work. She's not someone whose career or life depends on my word and my decisions. It's completely different."

"Point taken. Anyway, I have a bottle of lube in my coat pocket – I brought it with me, knowing I was coming here. Ah – I dropped my coat on the floor, didn't I…? Oh, there."

The fresh level of bizarreness their exchange had elevated itself to left Mycroft feeling a little unbalanced – possibly from the absence of oxygen, or good sense, at this stratospheric height of lunacy.

"You put a bottle of lubricant in your coat pocket, knowing you were going to your brother's house?" Mycroft asked, in the tone of voice he reserved for speaking to the criminally insane with goldfish-level intellect.

"Yup," Sherlock gasped out, returning to the bed after having stretched out like a very lithe and very naked cat to reach his coat where he'd left it on the floorboards.

"The Freudian psychologists would have a field day with us," Mycroft yielded to the familiar sinking sense of resignation he experienced too often when he was with Sherlock.

"You'd never let them anywhere near us," Sherlock grinned, thumbing open the flip top of the small bottle. "So, do you really want this and all your ejaculate in your expensive sleepwear, or can I just take off your clothes already? Andromeda was chained naked to a rock by the sea – Perseus got a pretty good eyeful at first sight. Mine's wearing Tana lawn pyjamas."

Mycroft groaned for what felt like the fiftieth time since the sun had gone down. "Sherlock, if I'd been chained naked to a rock as a sacrifice, I'm fairly certain the monster would have declined to eat me."

"I think you're selling yourself short," Sherlock declared. "I'd have eaten you."

"You always did have rather poor taste," Mycroft stated dryly.

"Bollocks. I have brilliant taste."

"Says the non-virginal virgin sacrifice who has just uttered the word 'bollocks' like a peasant and is kneeling naked on my bed clutching a bottle of supermarket-variety lube."

"Oh, this brand not good enough for your dick, brother dear?" Sherlock asked.

They regarded each other in silence for two and a half seconds, then one of them snickered – Sherlock, probably. Mycroft followed suit, and all the stiffness dissolved out of him. Sherlock saw him relax – of course he wouldn't miss the signs – and he snapped the bottle of lube shut, tossed it aside, and leaned over to kiss Mycroft deeply.

"You're beautiful, Mycie," Sherlock whispered huskily when he surfaced for air. "You're not pretty, but you're beautiful."

"My blushes, Sherlock," Mycroft huffed.

"Let me," Sherlock tried again, and this time, Mycroft let him unbutton and remove his pyjama top, as well as slip the pair of bottoms off him.

Not being in charge made Mycroft uneasy. But Sherlock must have sensed that – he had to have sensed it from his embarrassment yesterday and today about being the one to be chased, wooed, and won. And Sherlock adapted to his unease now that all the chasing and teasing was over, by sliding off the bed and kneeling on the floor between his legs as Mycroft sat on the edge of the mattress.

Mycroft threaded his fingers through Sherlock's hair as he felt his brother's breathing – and his own – accelerating. It was reminiscent of Serbia, Sherlock very nearly brought to his knees and left at Mycroft's mercy, despite his later bravado about being the one who'd got himself out. Bullshit, little brother.

"Get on with it, then, if you really want to," Mycroft said gruffly, with more than a touch of fondness in his voice.

Sherlock smirked and kissed Mycroft's cock before laving it with his tongue, then taking his balls carefully into his mouth, making Mycroft pant a little. In a minute, he returned his lips and tongue to his now fully erect member and gave it the most thorough attention. Mycroft inhaled sharply as Sherlock took him in right to the back of his throat, and his breath stuttered back out of his lungs in three staccato beats when he began moving up and down the shaft with only the briefest of pauses to circle the head with his tongue and dip lightly into the slit.

Mycroft cradled the back of Sherlock's head with one hand – not to pull him in or push into him, but to say: Not so deep, I don't want you to gag. Sherlock knew what he meant, but hummed a refusal around his cock, sending penetrating vibrations through his flesh that thrummed in his blood and shot up into the core of his body.

"Oh God, Sherlock," Mycroft moaned, leaning forward over the dark head buried in his crotch, wanting to get closer to his brother, and knowing at the same time that the position would force Sherlock not to take him in too deeply.

Sherlock grunted his disapproval, sending more vibrations through Mycroft, but he didn't give in this time, maintaining his posture, cradling Sherlock's head in both his hands now, steadying him, keeping him from taking too much, too fast.

So many nights, alone in his bed in their parents' home, or at university, or here in London, he'd guiltily indulged in illicit fantasies about Sherlock, swiftly dismissing the sensual images from his head back when the boy had been only 14 or 15, his youth compounding what was already a terrible desire on Mycroft's part. He'd let the images in more freely only when Sherlock was older, but even then, it was an impossibility, surely – the young man had nothing but contempt for him. And on the one terrifying occasion that, as a 17-year-old, he had offered himself to him, it had been on such cold, manipulative, transactional terms that Mycroft had been horrified. But he hadn't been able to stop dreaming, not when his brother was the most beautiful thing in his life, the one he'd watched intently for so long that it had birthed an impossible desire that would probably never depart from him as long as he lived.

Not impossible any more, though. For now, at least. Perhaps only for today. But if so, it was more than he might have hoped for, once upon a time.

Sherlock worked him beautifully with his mouth even with the restrictions Mycroft placed on how deep he could take him, and he felt the familiar build-up of tension winding up to the peak that was to come. Sherlock sensed it too, and opportunistically eased Mycroft back so he was forced to lean backwards and support his weight with his hands on the mattress, giving Sherlock more room to work. Given his head, so to speak, he didn't let up at all, quickening the rhythm, increasing the depth, making Mycroft moan over and over again until he climaxed with a stifled cry.

Breathing hard and resisting the urge to fall back bonelessly onto the sheets, Mycroft struggled upright and once more leaned forward to cradle Sherlock's pretty face in his hands, only to see him swallow, and lick a smear of cum off his lips. And good lord, if that alone wasn't nearly enough to make him hard all over again…

"Do you want to rinse your mouth?" Mycroft asked hoarsely, panting beside Sherlock's cheek.

Sherlock shook his head. "No, I love the taste of you."

"God, Sherlock…"

"You're perfect, Mycroft. Fucking perfect."

"That mouth of yours…"

"I'll use it on you again, any chance we get," Sherlock purred. "For now, I promise I'll go to sleep if you will too. The sun won't be up for another hour. I'm certain you haven't had enough rest either since you returned from your trip."

"Hmm," Mycroft hummed out his vague assent.

"Make those enemies of yours sweat a little longer over the letters we've retrieved. In fact, you should keep them on tenterhooks until tomorrow, or the day after."

"A suitably evil plan."

They climbed back into bed together and pulled the duvet over them both although it was too warm. Sherlock moulded himself against Mycroft's body and rested his head on his shoulder, one hand idly stroking the soft, curling hair on his brother's chest.

"Your mind's not racing so crazily now," Sherlock murmured sleepily. "That's good. I didn't like it. All that self-blame. You're absurdly hard on yourself."

"I don't think I've worked through it all yet," Mycroft warned, lazily tracing "Go to sleep" in symbols, codes and seven languages on Sherlock's back with the tip of his index finger. "And I'm still not certain that this was the best idea."

"This, us?" Sherlock asked tiredly, scrawling "Stop overthinking stuff" on Mycroft's chest.

"Do you know, the best-known myth I can find of two brothers shagging each other to kingdom come had sex between them imposed as a punishment," Mycroft sighed.

"Gwydion and Gilfaethwy," Sherlock mumbled. "Found that in your library too. Welsh myth – The Four Branches of the Mabinogi."

"Yes."

"Well, they were punished for raping a virgin girl – which, honestly, I can't see either of us doing," Sherlock muttered.

Mycroft snorted.

"And their punishment was to fuck as animals for three years and bear young to each other," Sherlock noted, barely coherent now. "But you know, animals don't get a whole lot of joy from copulating, so I'll bet they went right back to it for some fun after they resumed human form. You don't have sex with someone for three years in three different bodies and just forget them when you return to your original form, right?"

Mycroft chuckled a little bitterly. "Well, you're forgetting that Gwydion went on to have more incestuous relations, but with their sister this time. In human form."

"Don't think about it. Eurus is still locked up."

"Oh God, Sherlock!" Mycroft snapped, feeling the heat rising to his face as he delivered the sharpest smack he could to his brother's bottom. "Do not ever again mention Eurus when we're in bed together!"

"So you already know there'll be other times we'll be in bed together," Sherlock jumped on Mycroft's words, woken up a bit by the stinging smack. "I wonder what Mummy would say."

"Sherlock!"

"Sorry, couldn't resist making you go totally red all over – your body temperature's gone right up, you know, and we're hot enough as it is," Sherlock laughed. "Right. Promise I'll never mention another blood relative of ours when we've just had mind-blowing incestuous sex."

"You are the worst…"

"And that's why you love me," Sherlock mumbled, drawing a heart on Mycroft's chest. Almost certainly a substitute for sarcastically dashing off a tooth-rottingly sappy air on his violin, which he would surely have done if he'd had his instrument with him.

He fell asleep then, like a lightbulb switching right off, and Mycroft didn't have the heart to wake him with another sharp smack. (Anyone else would have been dealt a flogging.) As always, he was the exception to all the rules. His fantasies about Sherlock had come to life, for better or for worse – and perhaps only for now. But even if it turned out to be just for a day, Mycroft would take what he could get, after the twenty years he'd spent in the wilderness of despair.

Note:
Mycroft's line about his blushes echoes Sir Arthur Conan Doyle's Holmes when he says "My blushes, Watson!" in The Valley of Fear. But unlike Watson, who playfully tears Holmes down after the latter expects praise, Sherlock here means what he says to Mycroft.