Warnings: Teacher/student relations. Age difference. Innocence. Exhibitionism. Masturbation. Completely consensual, no underage.

"Mr Hummel, could you please stay after class?" Sebastian asks, without looking up from where he's scribbling in his notebook. As if on cue, the bell rings, and the students start to shuffle out. Kurt stops in front of Sebastian's desk, looking nervous and clutching the strap of his bag.

"Mr Smythe?" he asks hesitantly. Sebastian finishes writing out his notes on the students' behavior in today's class, then he looks up.

"I want to talk about your essay," he says, reaching for the pile of essays the students wrote during class two days ago.

"M-my essay?" Kurt asks, swallowing. "W-what about it?"

Sebastian flips through the pile until he finds Kurt's. "It's not really what I expected of you," Sebastian says, taking off his glasses and leaning back in his chair. "You're usually much better than this, Kurt. What happened?"

Kurt bites his lip and blushes.

"I'm sorry, sir," he mumbles, not quite meeting Sebastian's eyes. "It won't happen again."

Sebastian rights his chair again, trying to make eye-contact with his student. "Hey, Kurt. I'm just worried about you, okay? You're the best student in this class, probably in your whole year, but this is severely below your standard level. I noticed you were distracted in class today, too. Is everything alright?"

Kurt looks down at his shoes, but Sebastian can still see him blushing even harder. "Yes, everything is perfect," he mumbles.

Sebastian sighs. "Kurt, look at me." Kurt hesitates, but eventually raises his head. His pupils are blown wide and his lips are wet and fuck if he isn't the hottest thing Sebastian has seen in a long while. "Do you want to tell me what's been bothering you during my class?" Sebastian asks gently. "I promise everything you say will stay between us."

"I— not really, sir?" Kurt tries, shifting his weight and hitching the bag higher up on his shoulder. Sebastian fixes him with a glare.

"Kurt. I can overlook one bad essay. I can overlook you being distracted in one class. But if this happens more frequently, it will affect your straight A's. If you tell me what's bothering you, I might be able to help you."

Kurt is silent, but Sebastian can see the internal debate going on in his head. However, nothing could have prepared him for Kurt's answer.

"It's you," the boy blurts out.

"I beg your pardon?"

"It's you. You're distracting me." Kurt is back to staring down at his shoes, his cheeks flushed bright red.

Sebastian swallows. "I'm— okay. Would you… care to elaborate on that?"

Kurt shuffles again and focuses on the edge of the desk rather than on his shoes. When he talks, it's low, and he's obviously embarrassed. "I'm just… I don't know what it is, but when I look at you, I get all— fuzzy, inside. Warm, kind of. And it— it kind of goes down there."

"Down—" Sebastian's voice breaks, and he coughs before he tries again. "Down there?" he echoes.

"Down in my— please don't make me say it, Mr Smythe," Kurt pleads, looking up at Sebastian with wide eyes. "In my pants," he whispers; it's as close as he can get without humiliating himself completely.

Sebastian has to close his eyes and take a steadying breath. His student is attracted to him. His just-turned-legal, very good-looking straight A student, who's literally the definition of a blushing virgin, is attracted to him.

"I'm sorry, sir," Kurt says, sounding desperate. "I just, I really don't know what to do about it, and I tried thinking about something else, but then you bent over to help Lee with something, and I just, I'm sorry, but—" He's rambling, and Sebastian opens his eyes again.

"Kurt," he interrupts. Kurt snaps his mouth shut. "It's— it's okay," he says, even though it according to every rule isn't.

"Really?" Kurt says, and he sounds so hopeful. Sebastian stands up and walks around the desk, perches on the edge of it, in front of Kurt. He smiles, hopefully encouragingly.

"Have you… Do you know about masturbation?" Sebastian asks, cringing at the bluntness but guessing that it's the only way to go. Kurt just looks at him, confused.

"No. What's that?" he asks.

Sebastian would be surprised that a boy at Kurt's age hasn't heard about masturbation, but considering his lack of friends and barely no contact with his father due to boarding at the school, he really isn't. He doesn't know if it makes the situation more or less awkward, though.

"It's when you… relieve yourself. I think it could help with your— problems. You wouldn't be… as distracted. I wouldn't… affect you, as much."

"Okay, so what do I do?" Kurt asks, eagerly. Sebastian wonders how this became his life.

"Well, basically, you… When you look at me, when you get these feelings? Do you— does your penis get hard?"

Kurt looks scandalized, still blushing furiously, and he looks like he wants to sink through the ground, but eventually he whispers a silent "Yes."

"Okay," Sebastian says, trying to sound encouraging. "That is— good. When that happens, it usually feels better if you apply pressure. Have you tried that?" Kurt nods, his gaze nailed to the floor. "Okay. So. To make it feel even better, you can take off your pants and underwear, and then you— grab your penis, with your hand."

"That's dirty," Kurt whispers, still not looking anywhere but the floor.

Sebastian snorts. "No, it isn't. Masturbation is completely normal and almost everyone does it. It feels good." He grabs Kurt's arm and pulls him a little closer. "Kurt, it's not dirty. Do not feel guilty about doing it."

"But, do I just… hold it?" Kurt asks, his eyes flicking up to meet Sebastian's for a nano second, before fixing on the edge of the desk again.

"No, you… pull it, kind of. Drag your hand back and forth. And then just… whatever feels good, really. It's very individual. It may take a while to get the hang of it, but don't stress it. Take your time."

Kurt is silent for a long while, then he swallows and licks his lips. He looks up at Sebastian with determined eyes. "Will you teach me?"

—

If asked, Sebastian won't be able to tell exactly how it happened, but somehow, he ended up sitting at the edge of his desk in a locked classroom with a student standing half-naked between his legs.

Half-naked from the waist down, his back to Sebastian, with Sebastian's hand on his hard, leaking cock.

"Tell me if you want it harder or faster," Sebastian murmurs into Kurt's neck, tightening his grip around the untouched cock, jerking slowly back and forth.

"This— this feels good," Kurt chokes out, closing his eyes and letting his head fall back on Sebastian's shoulder.

"No," Sebastian says, jerking his shoulder to make Kurt raise his head again. "I want you to watch. I want you to watch your classmates' desks and imagine you're in class." He drags his thumb through the precome that has gathered at Kurt's slit. "Imagine I'm doing this to you in front of all of them. You'd like that, wouldn't you?" Kurt moans and closes his eyes briefly, but snaps them open when he remembers Sebastian's order.

"You can—," he breaks off, swallows, tries again. "Faster," he says.

Sebastian obeys and starts jerking faster, tightening his grip a little. It's dry, though, the leaking precome not enough to cover Kurt's admittedly impressive length, so Sebastian releases the cock and lifts his hand to lick it. Kurt whimpers at the loss of contact, but when he angles his head to see what his teacher is doing, his eyes get even wider.

"What are you doing?" he squeaks. Sebastian smiles at him around his fingers.

"I'm making it better," he says, and takes Kurt in his hand again.

"Wh— oh," Kurt breathes when he feels the change, how much better it is. "Oh my god."

"Keep looking," Sebastian tells him, nudging his shoulder blade. "Keep imagining being on display. You like that, huh? You like performing?"

"Uh-huh," Kurt agrees, struggling to keep his eyes open. Sebastian goes faster without being asked. This will be over pretty soon.

"I bet you're gonna come so hard over my hand," he says, using his other hand to stroke over Kurt's chest and pinch his nipple through the standard-issued uniform shirt. "You're gonna come, imagining I'm doing this to you in class, in front of nineteen other boys, and they will all be hard by watching you, Kurt."

"Please, sir," Kurt pants, and he sounds like he's close to tears. "I'm— it feels like—"

"It feels like you're gonna explode? Like there's something tugging inside of you, wanting to burst out?"

"Yes, please, I'm—" Kurt is writhing in Sebastian's arms now, not knowing what to do with himself, and Sebastian probably shouldn't find it as insanely hot as he does.

"Let go," he whispers in Kurt's ear and nips on his earlobe. "Just relax and let it go, Kurt, don't hold back."

"Oh god, I'm gonna—" Kurt clutches Sebastian's thigh and squeezes his eyes shut, despite the orders. Sebastian supposes he can't blame him. He jerks him a couple of more times before Kurt's whole body goes rigid and he spurts hot, sticky come all over Sebastian's fist. "Oh god oh god oh god," he chants, jerking his hips and fucking into Sebastian's fist, milking out his orgasm, riding on pure instinct. When he stills, Sebastian releases his cock and frowns at his come-covered hand. Kurt is boneless in his arms, so he glances around himself for something that's within reach, and his eyes land on Kurt's essay. He wipes his hand on it, thankful that it's not something he has to save for grading, and then turns his attention to the boy in his arms.

"That felt pretty good, huh?" he says, smiling. Kurt cranes his neck to look at him.

"That was amazing," he says incredulously. He lets go of Sebastian's thigh and stands up on his own. He reaches for his pants and dresses in silence, the situation appearing to catch up to him.

"I meant what I said," Sebastian says when it becomes apparent that Kurt isn't going to say anything. "This will stay between us." There's a stern note to his voice, and Kurt nods quickly.

"Of course," he says. He straightens his shirt and hoists his bag up on his shoulder again. "Thanks for the help, Mr Smythe. But, uhm…" he glances quickly around the empty classroom. "Honestly? I don't think this was helpful to my… situation."

Sebastian raises his eyebrows, pretending to be shocked. "You don't? That's too bad. Maybe I'm gonna have to tutor you. Make sure you… really learn everything you need to know." He palms himself, not bothering to try and hide his erection. Kurt's eyes follow his hand's movement and he swallows.

"Yeah, that— that would probably be good," he says.

"Good. You're dismissed now, Kurt."

Kurt nods and walks to the door. He unlocks it, but just as he puts his hand on the doorknob, Sebastian calls out to him.

"And Mr Hummel?" Kurt turns around. Sebastian smirks. "Be sure to practice what you've learned today. There will be a practical test next time."

A/N: Okay, because all the comments I've gotten so far have been about this: This is a one-shot. I don't really like teacher/student dynamics outside of roleplaying, but I got two prompts for this on my tumblr, and I woke up with half the fic in my head, so I wrote it. I'm not gonna write more in this 'verse, though. Sorry.