Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/ works/1050654. Rating: Explicit Archive Warning: No_Archive_Warnings_Apply, Underage Category: M/M Fandom: Sherlock_(TV) Relationship: Sherlock_Holmes/John_Watson Character: Sherlock_Holmes, John_Watson, Mycroft_Holmes Additional Tags: First_Time, Kissing, Frottage, Plot_What_Plot/Porn_Without_Plot, Alternate_Universe_-_High_School Stats: Published: 2013-11-19 Words: 1558 ****** Exothermic ****** by plushiebird Summary This is and extra chapter to my previous fic "Reacción Exotérmica" It is funny because, that fic is in spanish and this is in english. Highschool AU! You don't really need to understand all the back story, just think of this like a PWP with a bit of subplot. Notes Sherlock is 17, so rated Underage. See the end of the work for more notes One month have passed since Sherlock had made the principal laboratory explode, there wasn’t a lot of damage actually. Just a few of the windows had broken and two of the worktables had been affected. Mycroft had managed not to castigate severely his little brother, just a three days suspended from the school and two months of “social service” inside the school. And that “social service” included John Watson, they had to clean all of the laboratories in the C Building, every day for two months and in the weekends they had restore  the principal lab. The first day after Sherlock’s suspending time they had to clean and broom and mop. The next days they had to paint and replace the damaged furniture. John wasn’t very happy with all of the extra work, neither he was really angry about it, after all that little adventure had ended up with him and Sherlock snogging in his room. Today, (the 24th day since the service started) they are cleaning the various little and delicate crystal instruments actually John is the one who is doing it, he’s afraid that Sherlock might break them. He is sitting next to him, watching how John cleans, dries and places the items in their holders. Sherlock is thinking about his relationship with John, since their first kiss everything had been fine, John holds their hands together when they are in the chemistry class, Sherlock attends some of his rugby trainings, they have lunch together, in Mondays John sleeps in Sherlock’s room and in Fridays Sherlock sleeps in John’s. Sherlock scowls; the verb “sleep” is one of the most hurtfully accurate words to describe what they are doing in bed together.  Of course they have passed the “just kissing” stage, but neither they have reached the “almost sex” stage. Usually John is the cockblocker, like last Monday night; Sherlock had been sitting on John’s lap, kissing furiously and desperately, the three first buttons of this shirt were unbuttoned and John’s shirt was missing. Sherlock let out a rather loud moan when John sucked hard on his neck; a bruise forming already. They started to grind against each other and when Sherlock attempted to reach his belt, John stopped moving and took hold of Sherlock’s hands. “I think we . . . uhm, should stop now.”And then he moved Sherlock to the side and went straight to the bathroom. Sherlock changed into his pajamas and waited for John in bed, he hugged him and they spooned for a while before falling asleep. John’s voice brought him back from the memory. “Sherlock, what are you doing? Come here and help me with this box!” Said box contained new material for one of the university’s important investigations, therefore, Sherlock wasn’t allowed to touch it son the end John had to carry it from one corner to other of the lab. Actually, most of the hard work was John’s duty, Sherlock just observed him from one of the corners of the room, telling him what to do, complaining about how this was a waste of time and telling him all of his findings while deducing people. John was starting to get sick of it. “John, we have to go now, its 6p.m. already. Our cleaning shift have finished” “Our? Our?!You have done nothing more than stare at me since last Saturday” John approaches Sherlock “You know, in the Wednesday rugby training Greg tackled me and I’ve got a nasty pain in my leg and, well surely you already knew about it thanks to your “observing skills”.” Sherlock raises an eyebrow and apologizes; he doesn’t really like to make John angry. “Sorry, this is just too dull for me and you know it John, let’s just go and get some rest okay?” John sighs and rests his head in Sherlock’s shoulder, he inhales and smells Sherlock’s scent, it sends shivers down his spine and straight between his legs. John smiles and hugs Sherlock, making their bodies touch from head to toe; he raises his head and kisses him. Sherlock’s response is immediate, he opens his mouth and let John’s tongue in, the feel of it exploring his mouth touching with his own tongue is intoxicating. God, kisses hadn’t been enough since the last week. Sherlock needs more, more of John touching him, more of John’s warm hands kneading his arse and John’s teeth leaving marks in his neck. Sherlock moans when John bites his bottom lip. “John, ah. John, let’s go to your room now.” John separates and pulls Sherlock by the wrist towards the lab’s door. “God yes Sherlock, yes!” They walk fast all the way from the C building to the second students building. A few of girls stare curiously at them but Sherlock ignores them, he is focusing in the way that John behaves when he’s aroused. Possessive, frantic, desperate. When they reach the door to John’s bedroom, Sherlock is suddenly pinned to the wall and his neck is being attacked again, John sucks hard in his Adam’s apple and forces Sherlock’s thighs open with his right knee. He bites back a moan and reaches in John’s back pocket for the keys and hands them to him. John opens the door and practically shoves Sherlock inside, and then he slams the door shut and stares at Sherlock, he is sitting in the corner of the bed, with his knees wide open, the tent in his trousers is obvious from the angle of view. He is panting and a pink flush is covering his perfect cheekbones, his eyes are glowing with lust and the lightest bright of fear and innocence. And then it hit John, the same guilt that is there every time they become a bit more excited than normal. “God, Sherlock we can’t do this” John hits the back of his head with the wall and sighs. “You are still seventeen Sherlock; your brother would kill me if I do anything to you” Sherlock scowls and asks John no sit beside him in the bed, hesitantly John obeys and sits. Sherlock leans down and kisses John chastely, just a brush of lips, he hugs John and starts whispering in his ear. “Mycroft won’t do anything; I don’t know why you are so worried about him.” John closes his eyes and lies down in the bed, with Sherlock still on top of him, his hands rest in either side of Sherlock’s waist. “You don’t have to be worried about me either. I want it, for god’s sake John I want you to touch me, I want to feel you with me” Sherlock can feel the little tremors running up and down in John’s body; he can feel the other’s arousal pressing in his left thigh. John’s left hand reaches the back of his neck and then John is kissing him, a light but meaning kiss, John is still asking for permission. “Yes John, yes. I want it” And that makes it for John, he flips them over and starts to unbutton Sherlock’s shirt. God since the first day he had wanted to rip off those too tight shirts from Sherlock’s chest, when the shirt is out the way John sits and takes off his jumper and shirt. Sherlock runs his hand over John’s chest he has nice abs, not to pronounce but perfect for him, he licks his lips while John unbuckles his belt, he reciprocates and soon they are just wearing their boxers, John’s are blue and Sherlock’s are black. Suddenly, all of the rush is forgotten and John runs the pad of his thumbs over Sherlock cheekbones, they smile to each other and they whisper “I love you” at the same time. Their kiss starts gentle but soon it becomes rougher, faster and desperate, John loves to draw out harsh moans from Sherlock, so he bites at his lips and sucks his tongue inside his mouth. After a few minutes Sherlock is grinding his hips against his, begging silently for more. John smiles and slips his hands between their bodies, drawing out Sherlock’s arousal from his underwear. Sherlock gasps and grips the sheets when John starts pumping in a steady rhythm, long and strong strokes, sometimes just the tips of his fingers tease the head and when John runs the pad of this thumb just below the fraenulum Sherlock feels the heat starting to pool in his low abdomen. “John. . .” “Yeah, just relax Sherlock” They kiss again and Sherlock makes an embarrassing noise when he feels John’s cock touching with his’. He wraps his legs around the other’s waist and his arms surround John’s neck, he is panting into his neck. John closes his eyes and concentrates in the feel of Sherlock all around him, his arms holding him tight, his legs making them impossibly closer. They thrust against each other quickly and John can feel the exact moment when Sherlock tenses up and comes with a muffled cry. John turns his face to see Sherlock expression, his mouth is open in a silent scream and it’s all what John needs to come too. When John comes back to reality, Sherlock is dozing off. He smiles and wipes them clean with some tissues, then he rests his head in Sherlock chest and before falling asleep he whispers “I love you”. Sherlock smiles in his sleep. End Notes Again, feel free to point out any mistake. Thanks for reading! Please drop_by_the_archive_and_comment to let the author know if you enjoyed their work!