Snape 18+

Detention (not romantic or with any emotional connection, heterosexual)

You wake up from a girl shouting "gosh WAKE UP( y/n) we're late!"
Shit! You think, you're late potions class! You put on your robe without a bra on since you couldn't waste another minute, you put on a not well buttoned shirt and some black tights, your friend couldn't wait for you so she sprinted to class and left you on your own. You grabbed your books and bag and headed to the classroom.
You are 15 minutes late for potions class and Professor Snape already has seen you breaking rules so you start heavy breathing as you open the heavy wood door of his classroom. The whole class whispers about the way you look and you cover your chest with your robe since Snape and the whole class can't stop looking and you start feeling uncomfortable "Miss (y/l/n) you're late 15 minutes, if you're too busy to attend my classes it's a sign that you shouldn't be here, and dressing appropriately is a school rule, 20 points from hufflepuff"
Said Snape "see me after class for your detention". He kept going with his lecture but you couldn't focus at all after seeing the look on his face and the fact that he covered himself with his cloak while observing your tight breasts for 3 seconds that seemed like a century. "Why do you look like that?" Asked Miranda "mind your own business" you answered annoyed after she interrupted your fantasies
"Miss (y/l/n) what's the difference between a werewolf and an animegas"
Said Snape "I don't know sir" you answered "very well 5 more points from hufflepuff for your classmate's behavior". The class now ended and the students got out, the room got filled with silence and the only people left the was Snape and you. You sat on your desk waiting for him to tell you what to do for detention.
"Pick up those books" he pointed at the corner of the room. "And remove your robe" he demanded while sitting on his desk marking. You removed your robe and turned your back on him, started picking up the books, he observed your delicate back and your legs wrapped around with your black tights and that almost too short skirt you found first thing in the morning when you were in such hurry, he got distracted by you and couldn't continue marking so he sat back on his chair and touched his member through his tight trousers when you weren't looking. "Bring them to me" he said while grabbing the essays again. You could feel the tension in the air and you could also feel something strange down in your area.
You got on his desk and you placed the books in front of him, you hand touched his hand which was oddly warm and stiff, immediately you felt the same tingling on your panties, your breasts started tightening as he just kept looking at you like he couldn't contain himself. He placed his look on the books giving you a second without his eyes nailed on your breasts, you unbuttoned a few buttons giving him more place to look since you understand what was happening and you were into it. "Can i go now?" You asked hoping he won't say yes
"We're not done with detention miss"
He said, "you will now take off your shirt" he said and stood up coming closer to you, you started unbuttoning your shirt but not taking it out completely, you tried to cover your tits slightly with it but failed since it was too see-through and your tits aroused and tight. "Now turn around, head to my desk" he demanded turning you around and placing your head on his desk, your behind was now against his member that you could feel was already erected, he started going around your butt with his fingers, rubbing your asshole through your panties and going through your clitoris, something that made you softly moan, he then spanked your ass hardly and got in front of you. He sat on his desk chair "miss (y/l/n) you think I haven't seen you, opening your legs in my class, running through with your fingers, now come here" you sat on your knees in front of him and started rubbing his member through his pants, unzipping it slowly, you got out his member which was fully erected and started jerking him off which made him grunt a little, after, you started licking the tip of his member looking at his eyes, finally seeing him being pleasured, As you started going inside and out he laid back his head letting a loud grunt that made you go faster and faster, before he comes, he leaned towards you and touched your chin gesturing you to sit on the desk, he licked your breasts and neck and started going down slowly, grabbing you hips as you laid your head on his desk, he licked your pussy, he went all around as you were moaning in pleasure, he licked your clitoris which made your whole body get chills, he continued licking your clitoris as you moaned harder and your breathing getting heavier "not yet" he said, getting his face away from your pussy, he started rubbing your breast with his big left hand while with the right hand he started going to your lady parts, looking at you in the eye, he slid his middle and pointing finger inside and started penetrating you slowly, he then slid another finger inside and started going faster and harder, he then pushed his cock against your pussy sliding it inside your warmth, he was going inside and out softly as you were getting wetter and wetter, he started breathing heavily and you started moaning in pleasure even tho it kind of hurt because his cock was huge. He started going faster and faster as he was letting out grunts and you could see that he wasn't being pleasured for a while now. He got out and turned you around on doggy style, he started going as fast as he could and you could feel his cock twitching inside of you, you felt pleasure taking over your body, as you started breathing fast and heavily, you finished before he did but there was no way you would stop until he reaches high pleasure, you started moaning loudly "faster Professor" he started going as fast as he could, he got out of you and turned you over, he placed his cock inside your mouth and while filling it he let out a loud grunt. You swallowed everything as he was licking your neck as you went through his long black hair. He told you to get dressed as he putted his huge cock inside his trousers and you buttoned your shirt and putted on your robe
"I'll misbehave more often" you said
He let out a smirk and a last glance while rushing out of the room, clearly pleasured and in clearly a better mood.