Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/1481080.
  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, Car_Sex
  Stats:
      Published: 2014-04-17 Words: 529
****** School Run ******
by orphan_account
Summary
     Written for this_prompt on the kinkmeme - Mycroft fucking underage
     Sherlock in the back of his limo before delivering him to school.
Sherlock huffed against the tinted car window until he could scrawl an equation
in the steam. The angle was awkward - kneeling half-naked across the backseat
of the car with Mycroft methodically fingering him open with fat wet digits -
but he'd had plenty of practice.
"It's, unh, patently ridiculous," he said, squirming unthinkingly as he
contemplated the formula.
"My dear boy," said Mycroft patiently, "most fifteen-year-olds are required to
attend school. This is hardly the injustice you imagine it to be. And the term
should be pi squared, not cubed." Mycroft pulled his fingers out and slapped
Sherlock's arse gently.
Sherlock scowled at the correction even as he obeyed the unspoken instruction
and climbed onto Mycroft's lap.
"You know perfectly well that I don't belong there." He gripped the back of the
leather seat as Mycroft rolled a condom on and lined himself up, then sank down
onto Mycroft's thick erection with ease. Mycroft hummed approvingly - it had
taken months for Sherlock to be able to overcome his body's resistance - and
rolled another condom onto Sherlock's cock (heaven forbid one of Mycroft's
shirts should be soiled). Sherlock rocked back and forth in shallow thrusts
that sparked pleasure up his spine as he analysed the implications of the
revised equation.
"Well, perhaps if you'd deigned to attend any of your exams then we'd be having
a different conversation," said Mycroft with impressive calm considering he was
balls deep in his younger brother's tight arse. Growing impatient, he gripped
Sherlock's sharp hipbones and yanked him down harder onto his cock.
Sherlock made a rude noise and began to stroke himself rapidly as Mycroft
fucked him, his forearm rubbing against the soft wool of Mycroft's suit jacket.
They were only a few streets away now - he'd just seen some fellow students
walking on the pavement - and Mycroft could never be persuaded to extend their
route if Sherlock didn't finish in time.
Glancing across at the rearview mirror he made brief eye contact with the wide-
eyed driver before the latter snapped his eyes forward, and Sherlock wondered
idly what blackmail material Mycroft had on this one and if he could deduce it
by the end of school.
The combination of the exhibitionist thrill of being observed and Mycroft's
increasingly rough thrusts served to tip Sherlock over the edge, and he came
silently as Mycroft slammed up into him for the final time. His orgasm lasted
for several long seconds, blooming throughout his body as his arse contracted
in a stuttered rhythm, and it took a minute before he could move again and
lever himself up.
Mycroft took care of both of the condoms, tidying them away while Sherlock
dragged his underwear and trousers back on and the car pulled up to the school
gates.
"Do try to stay out of trouble today," he called as Sherlock clambered out of
the car. Sherlock flicked an absent-minded middle finger as the car pulled
away, and grinned to himself as he made a bee-line for the Chemistry building.
He was well-fucked. He had a wonderful new experiment to run. And (best of all)
he could legitimately blame Mycroft for any explosions he caused.
Mummy would be furious.
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