An exploration of the relationship between the Holmes brothers, from their childhood to adulthood, and linking into canon. Warnings for explicit sex and incest. It is Holmescest, after all.

Dedicated to Lex, without whom this story would not exist.

Mycroft didn't know.

This was a relatively rare event. But, given who it was in relation to, not entirely unprecedented. He didn't know what to do, or what to say, or what would happen next. He had few points of reference, and was dealing with possibly the most erratic human being he would ever know.

It had been a year and a half. It had been intensely slow in passing. Mycroft had felt every day of it go by with impossible slowness. He had been busy, he had been mostly satisfied and occupied with work. The government was a spectacular place to be, and he was at the epicentre, he was the working mind, the hard drive as it were, of the entire government.

He had been with nobody. The relationship with his boyfriend had died almost instantly, eighteen months ago, and he hadn't found anybody since. He remained strictly solitary, which was probably better.

It was Sherlock's eighteenth birthday.

"I will be back here when I turn eighteen, and you will listen to me"

Mycroft had been avoiding his brother all day. He had been back in the estate for several days, and was not enjoying himself tremendously. Sherlock had been appearing everywhere; around corners, in doorways, watching him, quietly observing without making a single comment.

They had barely spoken. Mycroft was collapsing with the weight of things he could not do, and could never do. Not where Sherlock was concerned. Sherlock seemed to have relatively few qualms in comparison; he was emotionally stilted, by his own admission, but when faced with his elder brother he seemed to be surprisingly adept.

Having said that, he was hardly a romantic. Nothing he had done – on any level – was explicitly romantic; he enjoyed mocking his elder sibling, taunting him by wearing jeans that snugly cupped his arse, a shirt that managed to magically unbutton itself to show halfway to his navel, a T-shirt so tight it bordered on insulting.

Today, Sherlock was in a white shirt, and black jeans that were slung somewhere in the region of his hips. His hipbones were protruding slightly, hair hanging in loose curls about the nape of his neck, a stark contrast to skin so pale it literally looked like Sherlock hadn't been outside in years. His eyes were beautifully wide and open, eyelashes curling darkly upwards, lips caught in what was undeniably a pout. Designed just for the moments when only Mycroft could see him.

Mycroft wouldn't have been surprised if the boy wore lip gloss and mascara in an increasingly blatant attempt to seduce him. Yet they had decided – Mycroft had decided – that nothing could even be discussed until Sherlock was eighteen.

And now he was. And Mycroft had no idea what to do with himself.

Sherlock was magnificently badly behaved. Mycroft was not deluding himself. He wasn't even sure his younger brother was capable of more conventional forms of 'love'; he felt affection, he felt a draw towards people, certainly. Love was, however, a particularly complex emotional circumstance that Sherlock had precious little exposure to and probably didn't know how to deal with, even if it did register for him.

Sherlock draped around doorways, and leant over sofas. He managed to accidently brush Mycroft's crotch while reaching over for a very uncharacteristic hug, inspired by Mycroft's gift – a beautiful coat, woollen, that reached down to his ankles. Mycroft quietly told him that even if Sherlock grew an inch or two, it would still suit perfectly. And if it didn't, he knew a tailor that would be delighted to alter it.

As the evening drew to a close, Mycroft was preparing for Sherlock's inevitable intrusion. He slipped into the study, settling himself down against the desk, facing the door. He had taken a comfortable few fingers of scotch, just enough to make himself feel slightly foggy around the edges.

"Don't look round," a voice commanded softly from behind him. Mycroft had to laugh; naturally, Sherlock had utilised one of the passages behind a bookshelf, appearing directly to the side of Mycroft's desk.

"Happy birthday," Mycroft said straight forward, towards the door. He did as commanded, staring resolutely at the door. "Sherlock…"

"Shut up, Mycroft," Sherlock said coldly. He was suddenly a mere inch away, breath hot against Mycroft's ear. "I told you, you're going to listen to me. I'm eighteen now, you can't claim I'm too young or naïve. I know what I'm doing, and I know what I want, and I know what you want."

Mycroft felt lips whisper along his jaw line, shadowing towards his own slack lips. "Sherlock…"

Sherlock ignored him, pressing a lingering kiss on Mycroft, a soft, explorative gesture on Mycroft's part as compared to a rather frantic motion on Sherlock's. Mycroft sighed, remembering every aspect of Sherlock, years passing within moments as they kissed again after two painfully long years.

"Sherlock…"

"Yes, brother-mine?"

"Precisely – brother. I am your elder brother, I have a responsibility towards you…"

"You have a responsibility to make me happy," Sherlock breathed, into the shell of Mycroft's ear, shifting so he was standing in front of Mycroft as he leaned his weight against the desk. "And I have a responsibility to you, as well. You want this too, and I want to give it to you."

"Do you… are you sure you…"

"Shh," Sherlock soothed, surprising Mycroft; his brother was not an overly sexual being, barely tactile and emotionally severely repressed. Mycroft could not adequately fathom Sherlock's motives; he did not make sense, this absurd boy, this absurd and glorious and brilliant boy.

Sherlock seemed to have borrowed confidence for the moment; he slid down to the floor, brushing kisses through the fabric of Mycroft's shirt.

He mouthed Mycroft's clothed crotch, feeling the contours of his erection, covered by suit trousers and underwear. Mycroft found his eyes rolling back slightly as the sensations began to overtake reason.

Mycroft was panting very lightly, unable to believe the situation yet not overwhelmingly surprised. Sherlock had claimed to want this for two years; he should have been ready for this, prepared for Sherlock wanting to escalate to this level. Yet he hadn't believed Sherlock ever would, not really.

If Mycroft allowed this, there would be no going back. The Holmes brothers would have an entirely new dynamic, one that had a decent chance of getting them jailed for an extremely long stretch of time. In a British court, they would not be helped by homosexuality, or indeed the age gap, either. This was danger of the highest degree.

Mycroft could literally not recall a time when he had been so hard.

"Sherlock, you don't have to… I know you're not…"

"Mycroft. Don't think I have been idle. Two years have passed, and I did what you wanted; I found other partners, I practised. Reluctantly, I must admit; I had hoped to only experience you. Yet I attempted to learn, because I knew this moment would come. Now please, Mycroft. Let me."

Mycroft was rapidly losing coherency, something Sherlock found intensely attractive; Mycroft was the epitome of control. Seeing him losing that control entirely, becoming a product of chemicals and need was unbelievably arousing.

The concept of Sherlock training himself was the one that was tilting Mycroft over the edge; his brother thinking of him constantly, engaging in sexual activities to 'learn' how to pleasure… it was a dizzying concept.

Sherlock's fingers played at his trousers, working at the buttons, opening them to reveal Mycroft's plain white underwear. His tongue explored the hardness through the material, assessing, deducing in the way Sherlock always had about everything.

Deft fingers worked at the waistband, tugging downwards. "Sherlock…" Mycroft tried once again. Sherlock was not adept with sex, there was no way he was comfortable with this…

His thoughts came to an abrupt halt when Sherlock's lips closed tightly around him, Sherlock taking as much as he was able in one go. Mycroft's murmurs of his younger brother's name took on an entirely different tone; he kept himself still as Sherlock worked on him, more adept than Mycroft would have believed him capable of.

It wasn't precisely earth-shattering, and yet it was. On a purely technical level, Sherlock was not excellent; and yet, he was Sherlock, which ensured Mycroft forgave him absolutely everything. True, the self-restraint required to not sink deeper, push Sherlock further was almost overwhelming; he was a long way off from being able to take Mycroft's whole length, his gag reflex still sensitive. Yet he made up for it in other ways, and he was glorious to watch.

Mycroft was relatively certain that it was Sherlock looking up that undid it. Hands around his brother's hips, sucking hard, looking utter debauched – he glanced upwards, enormous eyes suddenly focusing on him, Everything Mycroft loved about Sherlock was in those eyes, from his ferocious intelligence to his stunning naivety.

He came with a sudden, muffled cry. Sherlock tried valiantly hard to swallow, managing most of it, as Mycroft pulled out. He sank to his knees, apparently unable to stand any longer.

Sherlock leant back, looking remarkably pleased with himself. He wiped his face gently, his moves languid. Mycroft beckoned him towards him, letting Sherlock lean against his chest as his brother continued to breathe shallowly, stars receding from his immediate vision.

Sherlock let a delicious whimper escape when Mycroft's hands began to track down his chest. Sherlock's hips were beginning to rock already, trying to gain friction from his jeans.

Mycroft stilled him with one hand, the other slipping further. He unbuttoned the jeans, sliding down the zipper, making Sherlock moan wantonly. "My… Mycroft, please…" he mumbled, straining for touch.

Sitting against the desk, on the floor in the study, Mycroft finally allowed himself to do what he had wanted for years: he took his brother's hard, naked length, and begin to stroke it.

Sherlock whined, bucking to find more, anything. He was going insane, lights were going off in and around his head. He wanted this, he wanted his Mycroft, his brother, to bring him off explosively rather than be anti-climactic and dull. This was anything but dull. Mycroft would never be dull.

Sure movements, the ability to tease Sherlock until he was mumbling Mycroft's name frantically, heat coiling rapidly in his stomach. "I'm going… I'm going to… fuck," he cried, body arching as he came in his brother's fist, effectively wrecking his trousers as Mycroft clamped a hand over his mouth.

"People will hear," Mycroft said by way of an explanation, his voice remaining utterly calm. "Mother would be quite distressed, I believe, if she were to find out about this."

Sherlock didn't reply, his brain swimming as his brother's strong arms wrapped around him. This was sex. This was how it felt. He was beginning to understand why people engaged in so much of it. It put an entirely new spin on everything, it utterly changed things. So many people claimed sex was incidental, but not like this, not when it was somebody like Mycroft, not like this.

Mycroft had been quite right in one respect; Sherlock had a notorious lack of interest in sex for somebody of his age, and was not naturally inclined towards… well. There was no deft way of saying that he was not the type to suck his brother off in the study, for the first time, in a place they could easily be caught.

"Thank you," Sherlock breathed, eyes shuttering, relaxed against his brother's chest. Mycroft curled a protective hand over his head, stroking through the soft curls, unable to believe it. The curse of being an elder sibling: a persistent difficulty in believing that the younger child could have reached adulthood. Consistent memories of a far younger being.

"Sherlock, you need to understand something," Mycroft said quietly, after a little while. Sherlock turned to him, eyes wide and inquisitive, pushing himself slightly away from the comforting strength of his elder brother. "I have wanted you for a long while, and in a sense not restricted to physical intimacy."

Sherlock began to interject; Mycroft held up a hand, trying to find space in which to speak. "I want to be in a relationship with you. A genuine, reciprocal relationship. I love you very deeply, and you are very important to me. I fear you will not be able to give me that type of relationship."

"I've been…"

"You've evidently had sex, yes, at least some forms of sex. Relationships are different. There is an inherent belief from both parties that they will share more than bodily fluids. I wish to be a part of your life, as much as I am able," Mycroft explained slowly. Sherlock raised an eyebrow.

"Little would change," Sherlock pointed out. "I'd like to have you around more, if you could. I know work is difficult."

"If we were to continue a relationship, nobody would be able to know," Mycroft warned.

"Who would I tell?" Sherlock quipped, with a slightly bitter smile. "I am not well liked. You are the only person who even faintly understands me."

"The curse of being a Holmes," Mycroft said indulgently. "I must confess, caring is hardly one of my more renowned skills. You are the exception, as I know you are aware."

Sherlock settled himself back on Mycroft's chest again, humming in contentment as Mycroft held him again, their legs a tangled mess on the floor and Sherlock's flies still undone.

"I'm going to university," Sherlock sighed, nuzzling slightly against Mycroft's chest in what Mycroft was almost certain was not a conscious move. "I will scarcely see you."

"I can visit, and we will both be here for stretches of the holiday," Mycroft said lightly, tone flippant, yet still holding his brother tighter. "We will have time."

"Your work rarely gives you time," Sherlock commented, not maliciously, merely observing. "This… relationship, if you wish to call it that. We stand to lose more than most."

"I am aware," Mycroft replied. "We may end up imprisoned. Certainly, our job prospects would be non-existent. What I am afraid of, Sherlock, is that you are still very young."

"Piss off," Sherlock said petulantly, making Mycroft laugh at the irony.

"You are going to university, into the real world. You will meet a great many people. I fear you may meet many that greatly surpass me; not, perhaps, in intellect, but in other areas I lack."

Sherlock rolled his eyes, and kissed Mycroft gently. "I doubt it," he said simply. "Mycroft, when I complete university, I will need somewhere to live. I would like it if I could live with you."

Mycroft was silent for a moment, considering. "You wish to move in with me?"

"If you'd like," Sherlock said with a strange half-smile, suddenly reclaiming the shyness he occasionally managed. "I would have nowhere else to go."

"You could forge your own life, I managed," Mycroft pointed out. Sherlock stiffened slightly, and shifted out of Mycroft's grasp.

"Do you want this or not?" he asked boldly, fixing Mycroft with an almost blankly cold stare. Mycroft paused, his heart beating too-loudly in his chest. Very slowly, he nodded. Sherlock shot a sideways smile, and returned to the comfortable padding of Mycroft's chest.

"Good."

To be continued in "Give".

Any reviews or concrit would be extraordinary. I am incredibly touched and honoured by the reception this series has garnered! Truly, it is just wonderful. Thank you.