
Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/1839685.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      Sherlock_(TV)
  Relationship:
      Mycroft_Holmes/Sherlock_Holmes
  Character:
      Mycroft_Holmes, Sherlock_Holmes
  Additional Tags:
      Sibling_Incest, Moral_Ambiguity, Morally_Ambiguous_Character, Underage
      Sherlock, Underage_Mycroft_(to_some_extent), Set_over_many_years, pre-
      ASiP, POV_Mycroft_Holmes, This_does_end_up_being_a_loving_relationship,
      However_do_NOT_read_if_any_kind_of_underage_bothers_you
  Stats:
      Published: 2014-06-24 Words: 2959
****** A Secret Lesson ******
by raregloves
Summary
     Sherlock had always had a remarkable ability to manipulate the people
     around him. Especially the people who loved him.
Notes
     Prompt: Could you maybe please write a love-y Holmescest fic? Errr...
     and please don't think I'm a huge freak for this (though, maybe I am)
     could there be some under-age-y-ness? I just really like the idea of
     Sherlock ALWAYS being in love with his brother, and always having his
     super gift of manipulation, so he can get Mycroft to do whatever he
     wants.
See the end of the work for more notes
Mycroft took his little brothers hand as they walked towards the pond at the
edge of the garden. It was a bright, windy day and the grass felt springy under
his bare feet.

Beside him, Sherlock was nearly skipping with excitement. He wanted desperately
to examine the life forms growing in the pond, and was tugging Mycroft forward,
trying to drag him. He was strong for a seven year old, Mycroft thought.

‘Tadpoles!’ Sherlock shouted. ‘And frogs and fish and mostioqos!’

‘Mosquito,’ Mycroft said. ‘And I don’t know if we’ll see any tadpoles,
Sherlock.’

‘I love learning things with you,’ Sherlock said, beaming up at Mycroft.
‘You’re so smart.’

Mycroft smiled, pleased. None of his classmates appreciated intelligence in the
same way his brother did. They were concerned with kissing, and competing about
who had watched the most explicit movies. Sherlock was holding a basket
containing a number of jars in his other hand.

They reached the edge of the pond. Sherlock let go of him to rush forwards,
jars clinking. He wasn’t allowed near the pond without supervision. Mycroft,
who had no desire to stand in the mud, found a nearby tree and sat at the base
on a surprisingly comfortable root.

He watched Sherlock investigate the pond, enjoying the sun on his face and the
cool touch of the wind. Sherlock splashed about, collecting all kinds of things
in his jars: worms, beetles, moss…

Mycroft fell into a slight doze, lulled by the peacefulness of the day. But he
kept his ears open, in case something happened to Sherlock. Even the smartest
child could drown, after all.

But he must have fallen asleep. Because he woke with a start, some time later,
to the feeling of Sherlock pressing against his chest. His brother was nearly
covered in mud and clearly exhausted. He tucked his dark, curly head under
Mycrofts chin, breathing deeply.

Feeling affectionate, Mycroft ran his hand up and down Sherlocks back, soothing
him. They would probably be horribly sunburnt if they stayed, but Mycroft
didn’t have the heart to move him.
 
~
 
‘But Mycroft,’ Sherlock yelled. ‘I don’t know! I just want to know!’
Mycroft was desperately glad that their parents were not home to witness this
(mortifying) argument. He was quite sure he had never been so embarrassed in
his life.

‘You can read about it in books,’ Mycroft said. ‘You don’t need me to… show you
anything.’

‘You told me to know everything,’ Sherlock accused. ‘And now I’m trying to and
you’re not letting me because you’re mean and I hate you.’

‘You don’t hate me, Sherlock,’ Mycroft said, leaning down to put his hands on
Sherlocks shoulders. ‘You’re just upset that you have to follow the rules.’

‘What rule?’ Sherlock looked up at him, his face stained with tears, his blue
eyes watery under the shock of dark hair that stood out so fetchingly against
the pale of his skin. ‘I never heard of no rule.’

‘Of any rule,’ Mycroft corrected. ‘It’s just… one of the rules.’

‘But we hate the rules at school,’ Sherlock said, still failing to understand.
‘You say the rules are dumb and they are. You just want to follow this rule
because you hate me now.’ 
‘I don’t- Sherlock-’ Mycroft tightened his grip on Sherlocks shoulders. The
idea that Sherlock thought Mycroft hated him- it broke his heart, made guilt
bubble up inside his chest. ‘Sherlock. It just isn’t a good idea. I mean, why
not look at yourself?’

‘That’s not the same and you know it,’ Sherlock said, sniffing. ‘You’re older.
You probably know all about this stuff.’

‘Well, yes,’ Mycroft said. ‘But that doesn’t mean-’
Sherlock was crying again, big fat tears running over his round cheeks. Mycroft
felt his heart twist.

‘But I r-really loved l-l-learning things w-with you,’ Sherlock sobbed. ‘You’re
the c-cleverest person I know, Myc-hic-Mycroft.’

‘I’m sorry, I’ll do it,’ Mycroft heard himself say. ‘It’s fine, I do love you,
it’s ok. Just… don’t tell anyone, ok? It’s a secret lesson. Do you understand?
A secret lesson. Just this once.

‘A secret lesson?’ Sherlock said, gazing up at him. His smile was radiant and
beautiful despite the redness of his eyes. ‘Thank you, Mycroft! Thank you thank
you thank you!’ 
Sherlock launched himself at Mycroft, wrapping his thin arms around his middle.
Smiling, Mycroft peeled him off, picking up the heavy anatomy book in his
hands. It would be twenty minutes before their parents were home. 
‘Come into my room,’ Mycroft said. ‘We’ll do it in there, very quick. Ok?’

‘Ok!’

They climbed the stairs into Mycrofts room, Sherlock almost skipping. Mycroft
felt himself smile despite his nervousness.

He locked the door behind them, just in case their parents arrived home early.
His heart was hammering inside his chest, almost painfully, but he looked at
Sherlocks keen face and knew he would go through with it.

‘Ok,’ he said, trying to take charge of the situation. ‘Open the book to the
anatomy. Head to toe. We can look at where bones are, and muscles, and where my
organs are, all of it.’ 
Sherlock opened the book to the required chapter. His reading skills were
advanced, but Mycroft thought the pictures helped as much as the index did in
this case. There was no mistaking the drawings for anything other than what
they were, after all.

He stripped off, blushing, feeling Sherlocks gaze on him. He had never felt
quite so pale, or awkward, or chubby before. But it didn’t seem to matter to
Sherlock, who was gazing at him with wide, wide eyes.

‘You’re got hair!’ Sherlock accused, pointing to Mycrofts groin. ‘I don’t have
any of that.’

‘You will, when you get older,’ Mycroft said. Sherlock nodded seriously.

‘It looks a bit curly,’ Sherlock said. ‘Curly like my hair. Can I touch it?’

Mycroft hesitated, but it was too late- Sherlocks hand shot out and ran through
his public hair. He had a fair bit of it now, and Sherlock tugged at it before
letting go.

He felt himself blush, and desperately hoped that Sherlock didn’t notice.

‘So will I look like this when I get older?’ Sherlock asked.

‘A bit,’ Mycroft said. ‘You’ll probably look better than I do.’

‘Better?’ Sherlock gaped. ‘Than you? You’re the best though.’

‘Better looking, then,’ Mycroft said, smiling, but Sherlock shook his head
firmly.

‘I won’t be better looking,’ he said firmly. ‘You’re the best looking.’

Mycroft laughed and Sherlock ignored him, turning the pages of the book and
flicking through them, his expression thoughtful.

‘Can we start with muscles?’

‘Yes,’ Mycroft said, feeling himself settle into teaching mode. ‘Let’s begin…’

~

Even though he was too old to be frightened by storms, Mycroft couldn’t help
the leap in his stomach as another round of thunder sounded over the house. He
could hear the windows shaking.

A branch had fallen on the shed, crushing it. Father was outside, in a hardhat
and raincoat, trying to assess the damage while their mother held a touch up,
trying to shout instructions over the howling of the wind.

Occasionally lightening would light up his room with an eerie blue glow.
Mycroft pulled his covers up until they were under his chin. He wished his
parents were safe inside.

He heard his door open and knew without looking who he would see there.
Sherlock, eleven years old not a week ago, in his blue pajamas. Sherlock always
pretended he wasn’t afraid of anything during the daytime. Mycroft knew better
though. His brother was afraid of many, many things.

‘Can I get in? Mycroft?’

Sherlocks voice was small, pleading.  He didn’t want to say yes, not really. He
just wanted to sleep, to get through the storm without worrying about his
parents or his brother or the house. He sometimes resented the expectations
people had of him. The oldest child, the smart one.

‘Please?’

But Sherlocks voice sounded so small. With a sigh Mycroft lifted his blankets.
Sherlock rushed over and burrowed in right away, his warm body wrapping around
Mycrofts.

‘Are you afraid of the storm, Mycroft?’

‘No, not really.’

‘Me neither,’ Sherlock boasted.

The wind threw a branch against Mycrofts window with a loud crack. Sherlock
screamed, hiding his face in Mycrofts neck. His curls tickled his skin, but it
seemed unkind to push him away.

‘It’s ok,’ Mycroft said, soothing Sherlock. ‘It’ll pass.’

‘You’re so brave,’ Sherlock said. ‘You know I love you?’

‘Yes, I know,’ Mycroft said, surprised. It wasn’t like Sherlock to ask
questions he already knew the answer to. Not unless he had some very good point
to make.

‘Good,’ Sherlock said. ‘And you love me back?’

‘Yes, naturally,’ Mycroft said.

 Sherlock wriggled up until they were nose to nose. Lightening briefly
illuminated him, making his pale skin look almost transparent for a handful of
seconds. Mycroft blinked.

In the following darkness Sherlock pressed his lips against Mycrofts. It might
have been a chaste kiss. Should have been a chaste kiss. But as Mycroft gently
pushed Sherlock back onto the bed (‘Sleep now, Sherlock…’) he knew it hadn’t
been. Sherlock was old enough now to know what he was doing.

Mycroft didn’t get much sleep that night.

~

Mycroft had been right: the older Sherlock got the better looking he became.
At fourteen Sherlock was growing like a weed. A weed with pointy elbows, a
breaking voice and a gigantic appetite for food and knowledge. He rarely slept,
and seemed (to Mycrofts perpetual envy) to be able to consume gigantic meals
without gaining so much as a kilo.

He had also discovered masturbation.

Mycroft had walked in on Sherlock four times in the past month. Each time
Sherlock had been very nearly entirely naked, his shockingly slim body tense
with desire, his fist pumping at his red, swollen cock.

Each time Mycroft had slammed the door shut.

The first time had been an accident, or so he had assumed. The second time
could have been an accident too. But three times suggested a pattern to him,
and by the forth time he was sure.

He could barely open a door in the house without tensing, now, unsure of what
he would see on the other side.
Furthermore, the longer it took for Sherlock to strike, the more wound up
Mycroft became. Opening bathroom doors filled him with terror. The laundry
wasn’t safe. He would never see the interior of the shed the same way again.

The worst part was the fact that he couldn’t delete what he had seen. It had
been so shocking, so intimate, and so damned deliberate, that it refused any
kind of denial, removal or eradication in his mind.

Truthfully, he could still remember every detail with vivid clarity. The way
the veins had stood out in Sherlocks arms, the shiny red of his foreskin, the
way he had looked up, mouth open, eyes fixing on his-

Mycroft felt haunted and, though he repressed the knowledge as best he could,
uncomfortable aroused. It was, he knew, some sort of experiment on Sherlocks
part. How far he could push his brother, how long would he be able to get away
with it…

How far would he take it? Mycroft pondered. How would he react, if he were for
some horrible reason unable to escape right away?

He didn’t know. And he hated himself for not knowing.

It was a Friday. Nothing had happened so far. Sherlock had remained fully
clothed the entire day, apparently too busy with his homework to bother him.
Sherlocks approach to homework was to antagonize his teachers by giving his
answers in a complex code. He made up a new one every week.

Mycroft sat in the living room, feeling cautiously peaceful. The fire was
crackling and Father was humming to himself as he washed the dishes. Perhaps
the experiment was over? Perhaps Sherlock had collected all the required data?

The thought was somehow disappointing. Mycroft internally scolded himself,
trying to find the source of the disappointment and kill it. As usual, however,
it eluded his best attempts at destruction.

Sherlock went to bed early without saying goodnight. Mycroft examined the code
he’d written all the answers to his homework in- an interesting blend of Latin
and hieroglyphics.

He spent a few minutes trying to decode it, pleased at how difficult it was.
Sherlock, though not as clever as he was, was undoubtedly the smartest person
he had yet come across.
Mycroft yawned. It was getting late, and he might as well get to bed. He
climbed the steps towards his bedroom, not even thinking about Sherlock.

He opened his bedroom door and stopped dead.

Sherlock was on his bed, utterly naked, two fingers stuffed up his arse, his
other hand slowly stroking his leaking cock. Mycroft felt as if he had been hit
over the head with something very, very heavy.

He staggered inside, closing the door, terrified of somebody coming upstairs
behind him. Sherlock was making soft little moaning noises, his eyes roaming
over Mycrofts body.

‘Sherlock-’

‘Mycroft?’ Sherlock asked, breathless. ‘I know you’ve been thinking about it.’

‘Sherlock, this is-’

‘Against the rules?’ Sherlock said, eyes flashing. ‘Or did you only like it
when I was seven?’

Mycroft felt his cock twitch, and his cheeks flushed in shame. Had Sherlock,
even then, been manipulating him, preparing him, working out how to get them to
this point? Had all those innocent touches, those pleading glances…

‘Give me a hand,’ Sherlock pleaded. ‘Mycroft, please…’

Oh god. When had he ever been able to resist Sherlock saying his name, begging
him, the word please on his lips?

He sat on his bed and linked his fingers with Sherlocks. His brothers cock
twitched at his touch, pre-come leaking from the tip and running down their
joined fingers, sticking them together.

‘I’ve got lube,’ Sherlock whispered. ‘Want your fingers in me.’

Mycroft knew he shouldn’t (knew he would, knew he should lock the door) but he
nodded. Sherlock withdrew his fingers and passed it over. The wetness of his
fingers made Mycroft bite down on his bottom lip to stop himself from making a
noise.

He slicked his fingers up as best he could one handed, figuring that Sherlock
was already stretched enough by his own fingers for it not to be too much of an
issue. Neither of them spoke.

He reached around, finding Sherlocks hole already wet and twitching. Mycroft
breathed through his nose, trying to focus on the way Sherlock sounded, and the
way their hands moved together. Anything to distract himself from his own
aching, aching cock.

He pressed in, both his fingers at once. Sherlock hissed at the stretch, which
was slightly more than Mycroft had anticipated it would be. His own fingers
were larger than Sherlocks, after all. He hesitated, unwilling to hurt his
brother but almost equally unwilling to withdraw from the heat clenching around
his fingertips.

‘Don’t s-stop,’ Sherlock said, almost lisping. ‘In, in.’

So Mycroft pushed, feeling the ring of muscle clench and relax a few times
around his knuckles before drawing him in. They sighed in unison, Sherlock
tightening their grip on his cock.

The angle was awkward, but not so awkward that Mycroft couldn’t lean down and
press his lips over Sherlocks. It strained his back, but was worth it for the
noise of surprise and pleasure Sherlock made as he opened his mouth.

Their tongues moved together, hungry, Sherlocks breathing now ragged.
Eventually he pulled away, eyes dark.

‘Mycroft, I’m not going to last-’

‘Of course you aren’t,’ Mycroft said, smiling. ‘You’re young. You’ll learn.
Come for me, let me see it.’

Sherlock closed his eyes. Mycroft twisted his fingers within his brother,
brushing over the slight bump of his prostate. Once, twice, three times, and
each time Sherlock stopped breathing, until on the forth he came, eyes screwed
shut, a low moan caught in his chest.

Mycroft watched, his own cock twitching in sympathy. His fingers ached as
Sherlock clamped down around them but he didn’t remove them, not until
Sherlocks cock had finally started to soften, and the muscles holding his
fingers in relaxed.

Sherlock seemed to melt into the bed, his eyes opening slowly. He smiled,
slowly, deep affection in his eyes. Mycroft felt his heart stutter in his
chest.

‘Do you want me to do anything?’ Sherlock asked, nodding towards Mycrofts lap.
Mycroft shook his head, almost overwhelmed.

‘I’d rather take care of it myself,’ he said, voice soft. ‘Sherlock… what we
just did…’

‘It’s ok,’ Sherlock said, leaning up and kissing him on the lips, kissing the
words away. ‘It’s ok. We love each other. And if you don’t want to fuck me
until I’m eighteen then I’ll wait, I will.’

Mycroft closed his eyes. Sherlock rested his head on Mycrofts shoulder. They
sat like that for a long time, the silence of the house reassuring Mycroft that
nobody had realized what had happened between them. Every rational cell in his
brain was telling him to withdraw immediately, to save them both from years of
pain and confusion. But it seemed impossible to him that being with Sherlock
like this could cause pain or confusion.

He realized that the hot, trembling feeling in his heart might in fact be love.

‘Oh Sherlock,’ Mycroft whispered at last. ‘What on earth are we going to do?’

‘We’re clever,’ Sherlock said, and Mycroft could hear the smile in his voice.
‘We’ll work it out.’

Mycroft nodded, taking Sherlocks chin in his hand and tilting his face until he
could look into his eyes. He saw peace, and lust, and trust all mingled
together in his brothers eyes.

With a sigh, Mycroft leant down and kissed him again.

They were clever. They’d work something out.
End Notes
     You can send me a prompt on my tumblr- I love rare pair fic :)
     raregloves.tumblr.com
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