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Xiao Zhan’s hand flies over the blackboard, chalk dust scattering behind him, and Yibo doesn’t understand a thing but he keeps staring, enraptured, hands propping up his chin.

He knew his boyfriend was a hot-shit math professor, an expert in numbers Yibo has never even heard of, but he never imagined it would be such a fucking turn-on watching him like this, holding court over a packed lecture hall as equations appear under his hand like magic characters in a scroll. Xiao Zhan’s talking as he writes, and the words don’t make sense to Yibo but everyone else is dutifully scribbling them down with mechanical pencils, the only noise in the silent room. When Xiao Zhan turns around, Yibo can’t help but admire the way his slim grey suit hugs his body, tapering from his shoulders to his narrow waist. As he faces the seats again, the open collar of his white shirt gapes over his chest as he gestures, unbuttoned a little more than it needs to be. When he moves, Yibo can almost see a flash of chest hair.

God, the kids in this class have it made, getting to stare at him like this all afternoon. Yibo, sitting in the back of the hall, would be jealous if he didn’t know who’s going home with the professor.

The lecture goes on for another twenty or thirty minutes, long enough for Yibo to shift in his seat, wishing he could check his phone to at least take his mind off the hotness in front of him. You have to set a good example, Xiao Zhan told him sternly, when he agreed to let Yibo sit in on his afternoon class before their date, but Yibo never expected he’d need the distraction from staring at his own boyfriend.

Finally, mercifully, the class ends. Xiao Zhan answers a few questions, and from the dry, expressionless way he answers them, Yibo can tell they’re stupid. That makes him squirm too, seeing Xiao Zhan stare down some dumb undergrad as he snaps his laptop shut and puts it in his leather satchel.

As we discussed,” Xiao Zhan says, adjusting his wire rimmed glasses, and Yibo thinks he would die, being dismissed like that by the hottest professor he’s ever seen. If he hadn’t dozed through most of his business classes before getting into public relations for a cool lifestyle company, that is. (In his defense, none of his professors looked like Xiao Zhan.)

The students have all left by the time Yibo saunters down the stairs, hands in the pockets of his loose-fit jeans, folded Ray-Bans hanging from the collar of his t-shirt. Xiao Zhan is standing at his desk, shuffling through some exam papers with a frown, and he only gives Yibo a brief glance before looking back down at them.

“Sorry,” he says. “I need to file these exams and then clean the chalkboard for the day.”

“I can do that,” Yibo says, and adds, “Xiao-jiaoshou.”

Xiao Zhan glances up again at the honorific, papers still in his hand, and this time as he looks down he’s smiling.

This will be fun, Yibo thinks, picking up the erasers. Cleaning the blackboard was always his favorite job in school, though he’s probably not going to clean the erasers by clapping them at Xiao Zhan until he’s covered in chalk dust, the way he used to with his friends. Probably not.

The chalkboard is big, and Xiao Zhan has covered it densely with his wide, sprawling, beautiful handwriting. It almost feels like a shame to erase it, but Yibo does anyway, enjoying the smooth swipe of the eraser through the dusty surface and scrubbing in big arcs until it’s clear. The task occupies him for a few minutes, and then he turns around and looks at Xiao Zhan again.

Xiao Zhan is standing slim and tall, glasses perched on his nose and dark hair falling on his forehead, a skeptical frown on his face as he reads the paper in his hand. His other hand is on his hip, pushing aside his suit jacket to expose the tight fit of his trousers and the crisp white shirt beneath, and Yibo has never in his life felt this horny for someone he’s been sleeping with for months.

“Xiao-jiaoshou,” he says, and he pitches his voice just a little higher, like it belongs to someone else.

Xiao Zhan looks up at him, lifting and turning his head very, very slowly. One eyebrow raises. “Yes?”

“That was a great lecture today,” Yibo says. He scrubs a hand through his hair, tousling it. “Really cool. But, uh, I didn’t really understand any of what you said.”

“Oh?” Xiao Zhan says. His posture is motionless, the exam paper still in his hand. There’s a faint smile around the edges of his lips, though, probably because this is a high level course with only mathematics majors in it, nobody like the friendly jock Yibo is pretending to be.

“Yeah,” Yibo says seriously. “I know I’m not going to pass this class. Unless maybe there’s something I could do to....raise my grade?”

Xiao Zhan swallows. Yibo sees it, the way his Adam’s apple bobs, and how he glances around the big, empty lecture hall. It’s the end of the day, but Yibo knows anyone could still walk in, from a student to a janitor to an administrator.

“You’re just a really inspiring lecturer, Xiao-jiaoshou,” Yibo says, and he sees it again, the way Xiao Zhan reacts when he calls him professor. “You’re so strict on us, but the way you talk when you’re in front of the classroom....” He trails off, smiling. “And besides,” he adds, taking advantage of his position as Xiao Zhan’s actual, real-life boyfriend, “your ass looks amazing in that suit.”

Xiao Zhan slams the paper down. “My office,” he says, and fuck, fuck, his voice is so stern it sends hot shivers all through Yibo. “We’ll talk in there. About your grades,” he says, with a withering up-and-down glance at Yibo that makes his heart race.

The walk to the faculty offices is altogether too long, and it seems like Xiao Zhan has to nod and greet a million people on the way. When he opens the door to the stairwell, for a moment Yibo has the wild idea of shoving him up against the wall, taking advantage of the privacy in here to shift the balance to something more like usual. But he likes the way Xiao Zhan is stomping along, barely holding the door open long enough for Yibo to catch it, and Yibo’s the one who started this game to begin with. He’s got to see it through.

Xiao Zhan’s office is at the end of a long hall, and Yibo is glad to see the window on the neighboring office door is dark. This time, Xiao Zhan holds the door for him, and when Yibo walks through, Xiao Zhan shuts and locks it behind him.

“Xiao-jiaoshou—” Yibo starts.

Xiao Zhan brushes past him, wordless. The office is small but he has it in good order, with the wall shelves on either side closely packed with books, binders, and file folders. On the back wall, there are a few pieces of framed art hanging up, more of those geometrical figures on black backgrounds that he has in his apartment, and between them there’s one narrow window with dusty blinds that Xiao Zhan pulls down with a snap, leaving them in just the flickering fluorescent light.

He stands at the desk for a moment, framed by the art behind him, leaning on his hands and looking at Yibo over the top of his glasses. The overhead lighting casts strong shadows around his eyes, making him look different, more severe. Then he sits down in the chair, leaning back to put his feet on the desk, one crossed over the other, with his arms folded over his chest.

“So,” Xiao Zhan says. He lifts his chin in a quick tilt, indicating the plastic chair in front of the desk. Yibo pulls it out and sits, his mouth unaccountably dry. He feels like they’re totally different people, like all the rules are different in here.

“Your grades,” Xiao Zhan says, and lets it linger.

“Yeah,” Yibo says. “They’re bad.” He tries a winning smile, sheepish and hopeful, but Xiao Zhan’s expression doesn’t change, stern as ever.

“Why are you in my class, Wang Yibo?” Xiao Zhan asks.

Yibo grimaces, and then offers the truth, both today and exactly what he would have said five or six years ago when he was still in school. “I wanted to take a class with you.”

The light coming in through the blinds is fading, making the room darker. It was sunny when he first got to the university campus, but clouds were already rolling in, and now it looks like the forecasted rain is on its way. Somehow that makes him feel young again, like every time he was stuck inside because the weather was bad, being hustled through schoolwork he didn’t care about.

Xiao Zhan probably never had to be hustled through anything. Yibo’s never met anyone as smart as him, and sometimes he just watches him work—Xiao Zhan’s long clever fingers wrapped around a pen as he scribbles out equations, or typing quickly when he’s working on a paper. It feels like Xiao Zhan’s always thinking, always in control.

He’s clearly thinking now, even though his face is still impassive. The truth is, bed is the one place where he usually seems relaxed, smiling and warm, happy to let Yibo take the lead. What’s happening today is a complete 180 from their normal dynamic, and Yibo has no idea what to expect next.

“You like taking a class with me?” Xiao Zhan finally says, softly.

Yibo just nods, watching him.

Xiao Zhan unfolds his arms and lifts his hands to link behind his head, stretching his shoulders. It pulls his grey suit coat up, his unbuttoned white shirt gapping more, and the bolo tie with a silver clasp rides up too. His eyes are so dark and intense that it feels like Yibo can’t breathe, waiting.

“Let me show you how much I Iike it,” Yibo blurts suddenly, breaking the silence.

At his words, Xiao Zhan’s eyes flash. He wets his lips. “A quid pro quo?”

“I don’t know what that means,” Yibo says, playing the dumb jock again. “But I’ll suck your dick if you give me a C.”

Xiao Zhan breaks into a wide, surprised smile, his white teeth showing, and for a moment the game is over. But he gets control of himself again, shaking his head, eyes narrowed.

“You kids,” he says, and then, whip-sharp: “Get on your knees.”

It feels like all the blood leaves Yibo’s head at that, and he hits the floor with a hard thunk, pain racing through him. He doesn’t care, though, waiting for the next command.

“Come over here,” Xiao Zhan says. “Crawl.”

God. Yibo does it, bending over so he’s on his hands and knees. He’s trying to keep his head in the game, playing a horny student getting to blow his hot professor, but all he can think about is how Xiao Zhan’s cock tastes, the heavy musky weight of it on his tongue. When he comes around the desk Xiao Zhan is sitting back in his office chair, knees splayed, impossibly long legs stretching out. Yibo crawls between them, feeling the dust of the linoleum on his hands, the way his heart is hammering so hard.

He stops, looking up. He puts on a friendly, hopeful smile, one side of his mouth drawing up, but Xiao Zhan just stares back at him, eyes stern behind his glasses, and puts one hand on the back of Yibo’s head.

“You know what to do?” he asks. “Or do I have to teach you how to do this too.”

Yibo flutters his eyelashes, dropping his chin a little. He knows what he looks like, when he wants to play it up like this. “You should show me how you like it, Xiao-jiaoshou.”

Xiao Zhan gives him a look, jaw tensing. His hand drops to his crotch, palming himself, and Yibo can see how he’s getting hard.

“And you should get more comfortable, too,” Yibo adds. “Take off your coat.”

Xiao Zhan reaches back, shrugging out of his suit jacket. At home, he’s always careful to put it on a hanger in the closet right away, but now he just tosses it across his desk, knocking off some papers, before sitting back in the chair. He unbuttons his shirt sleeves, rolling up the cuffs to show off his forearms, and Yibo swallows hard, watching him.

“Well, then,” Xiao Zhan says, resting his hands on the arms of the office chair. His long, narrow feet shuffle on the floor as he settles down and slides his hips forward. “Get to it.”

Xiao Zhan’s making him do all the work, Yibo realizes, and a hot shiver goes through him at how closely Xiao Zhan is watching him. He swallows again and reaches up to undo Xiao Zhan’s belt buckle and the button of his suit pants. Xiao Zhan’s dick gets harder when he brushes it, rising up, and Yibo takes his time, easing the zipper down.

Now he has to get up on his knees, leaning in as he takes Xiao Zhan’s dick out, hot and firm in his hand. He leans his other arm on Xiao Zhan’s thigh, and his glance flickers up for a moment, head tilted and lips parted, close to that heat.

“Tell me if I’m doing this right,” Yibo says, low. He lets his warm breath gust against the head of Xiao Zhan’s cock, trying to drag this out a little, wind him up.

Xiao Zhan puts a hand on the back of Yibo’s head, fingers closing in his hair. “I hope you’re better at sucking dick than you are at differential calculus,” he says, and pushes Yibo down on his cock.

This is familiar, the taste and the feeling, except Xiao Zhan’s never held him like this, never been rough with him for long and always with a smile, like he’s just too eager to be gentle. Now his grip is tight, controlling, and his hips pulse up into Yibo’s mouth, cock sliding over Yibo’s tongue, almost into the softness at the back of his throat.

Yibo loves it. He’s always happy with whatever they do, the hours they spend in bed enjoying each other, but there’s never this hard edge and it’s something he likes too. The way Xiao Zhan is just doing it to him, making him take it, like he wants Yibo too much to hold back. There were some early times when they got a little wild, even dangerous (the elevator in Yibo’s office comes to mind), but Xiao Zhan’s never shown what he wants so clearly, just taking no matter what.

He shoves in deeper and Yibo gags, surprised, trying to suck a breath through his nose at the wrong time. Xiao Zhan lets go right away, easing up. Yibo waits for him to apologize, breaking the mood of the game, but Xiao Zhan just strokes the back of his head, soothing but not retreating, as Yibo coughs and gets himself together.

“Can you keep going?” Xiao Zhan asks. His voice is still the commanding professor but there’s concern too, his thumb stroking the shell of Yibo’s ear.

Yibo nods, sniffling, and licks his lips. “Maybe work up to that,” he says, and he can already hear the hoarseness in his throat.

He puts his mouth back on Xiao Zhan’s dick and this time Xiao Zhan just keeps his hand on Yibo’s head, guiding instead of controlling him. It’s not as exciting, but now he starts talking, and that’s even better.

“You do this a lot, Wang Yibo?” Xiao Zhan asks, like he’s musing to himself. “You keep your grades up by blowing all your professors?”

Yibo shakes his head violently, no, as he keeps working over Xiao Xhan’s cock. Lips stretched over the head, his tongue flicking the salty slit, and then the slide down, taking it almost all the way in. He’s getting noisy now, slurping, and he can feel spit gathering at the corners of his mouth.

“Of course not,” Xiao Zhan says, and his fingers close in Yibo’s hair, gripping. “You’re just in this class because you like watching me, right?” Yibo makes a noise around his cock, and Xiao Zhan keeps going. “You probably don’t know that I’ve been watching you too. Tight jeans, always in the back row, looking like you’re about to fall asleep. You know when you’re zoning out, your mouth looks just like this? So pink and open. You’ve got a mouth made for sucking cock, Wang Yibo.”

Yibo groans around his dick at that, sucking harder, faster. His throat is warmed up now, soft and loose, and he pushes the fat, plush head deeper, feeling the warm brush of Xiao Zhan’s pubic hair against his lips every time he goes down. It’s so fucking hot, imagining Xiao Zhan looking at him the way Yibo was checking him out. Thinking about this, getting his dick in Yibo’s mouth.

“What if I said this wasn’t enough to get your grade up?” Xiao Zhan asks, his voice raspy. He tightens his grip, shifting his hips down and his legs wider apart. “What if I said you had to come here every day after class and blow me.” He’s breathing hard now, starting to push Yibo’s head down again, and Yibo lets him. “You’d get so good at it, Wang Yibo. You’d know just what I want. You’re so good for me.”

His hips rock, like he can’t help it, and Yibo feels how close he’s getting, the way his cock is swelling up so thick and hard. Yibo sucks him harder, loving how it makes his jaw ache, getting all that solid length forced inside.

“That’s it,” Xiao Zhan pants, sliding down in the chair with a groan, feet flat on the floor. He’s totally in control. Yibo relaxes and just lets Xiao Zhan fuck his mouth, Xiao Zhan’s hips pumping up to meet his head as Xiao Zhan drags him down. His cock is so big now, filling Yibo’s throat every time he thrusts in, and all Yibo can do is fight for breath, drool spilling out of his mouth and tears from the corners of his eyes. It feels intense, a little scary, and totally fucking amazing.

“Good boy,” Xiao Zhan gasps. “So good for me, maybe I’ll give you—”

He lets out a choked cry, thighs tensing and his back arching, and then there’s a sharp pain as he yanks Yibo up by the hair, wet cock sliding out of Yibo’s mouth just as he starts to come. Yibo keeps his eyes shut, and he can’t help gasping at the hot spurts that hit his face, shooting into his open mouth and dripping down over his jaw and throat. It feels filthy and shocking, being used like this, and Yibo loves it, loves that they’ve gone this far at last. Xiao Zhan’s still holding him tight, and he groans through it all, long soft shudders like he can’t keep himself quiet.

“Oh my god,” Xiao Zhan gasps, when he finally lets Yibo go, falling back against his seat with a squeak of the chair.

Yibo rubs his eyes with the heels of his hands, and then looks up at Xiao Zhan, who’s panting heavily with his head tipped back, eyes squeezed shut. He looks ruined, cheeks a hectic red, styled hair tousled, white shirt creased and pants still open with his spent cock hanging out. He looks like Yibo’s boyfriend, not the hot-shit professor Yibo’s been thirsting over for the last hour, and Yibo likes that just as much. Better, really.

“Xiao-jiaoshou,” he says, and then: “Zhan-ge.”

At that, Xiao Zhan’s eyes open, his flush going brighter. “Hey.”

He seems dazed, eyes dim, but they widen when he sees Yibo’s face. Yibo watches Xiao Zhan’s gaze flick all over, and his lips form a silent fuck under his breath.

Finally, Xiao Zhan reaches out with one hand, dragging his long, delicate fingers through the slick smears of come on Yibo’s jaw. He thumbs the center of Yibo’s swollen lower lip, catching another smear, and laughs, soft and embarrassed. It looks like he likes it, though, and Yibo takes his thumb in his mouth, sucking, flicking his tongue against the tip.

“Look at you,” Xiao Zhan says, low. His glasses have slid down his nose and he watches Yibo over the top of them, still breathing hard.

Yibo licks his thumb once more and then lets it slide out of his mouth, leaning back. “So,” he says, and wow his voice is so fucked up, husky and rough. “Do I get a good grade?”

He sees how Xiao Zhan’s breath catches at the ragged sound of his voice, and now Xiao Zhan’s eyes flash, like he’s only just remembering their game. He swallows, closing his eyes briefly, and then he’s back to the way he was before, eyes narrow and stern.

“I don’t know,” he says, impassive. “You’ll have to come back next week and we can see what you’ve learned.”

The tension stretches out just a moment longer, and then he smiles, wide and laughing, leaning forward and reaching for Yibo.

“Oh my god,” Xiao Zhan says, face tucked against Yibo’s neck, kissing under his ear. “I can’t believe you—come here, you must be so—”

They’re a tangle, both of them getting up and trying to touch each other, Yibo throwing his arms around Xiao Zhan’s shoulders and Xiao Zhan with his hand on the fly of Yibo’s jeans. They end up with Yibo leaning against the desk and Xiao Zhan straddling his thigh, and when they find each other’s mouths their words get lost in hot, messy kisses, breathless and whimpering. Yibo knows his face is still wet, and he knows Xiao Zhan must be able to taste himself on Yibo’s lips, and he loves how neither of them care.

“Fuck,” Xiao Zhan says, yanking hard at Yibo’s zipper and shoving his hand inside. He kisses Yibo harder, bending him over, with his other hand braced against the small of Yibo’s back. Yibo clings to Xiao Zhan’s shoulders and kisses back, groaning into Xiao Zhan’s mouth when he gets his hand around Yibo’s cock.

“Oh yeah,” Yibo gasps. He bucks his hips, head spinning with the aching, explosive pleasure of finally being touched. This whole time he’s been so focused on Xiao Zhan, but now he realizes how close he is, how desperate. “That’s good, fuck. Wish you could fuck me, Zhan-ge. Want you inside.”

Xiao Zhan was warming up to a good, fast handjob, but his hand slows like he’s thinking about that, and as much as Yibo wants to get off right fucking now, he can’t resist the opening to push a little further.

“You could put me over your desk, Xiao-jiaoshou,” Yibo says, and kisses him again. “With my pants down around my knees—”

“You want that?” Xiao Zhan asks fiercely. He tilts his head, leaving biting kisses along Yibo’s jaw. “You’d do anything to get your grades up? Let me use you like that?”

The bottom drops out of Yibo’s stomach, and he digs his fingers into Xiao Zhan’s back, hips arching into his hand. “Fuck yes.”

“Your bare ass out,” Xiao Zhan says. He starts to stroke Yibo’s cock again, slow and deliberate now. “Hanging onto the edge of the desk while I finger you, opening you up.”

Yibo nods, his throat tight, too turned on for words.

“Would you keep your hands there if I told you to?” Xiao Zhan asks. He’s speeding up now, Yibo’s foreskin slipping back and forth over the head of his dick with every stroke. “I can’t fuck you again right away, so you’ll have to wait.”

He bites the side of Yibo’s neck again, sucking a mark, and Yibo’s eyes roll back until he’s staring at the top of the tall shelves behind Xiao Zhan’s desk. Something catches his eye there, narrow and curved and golden. The abstract shape of the department prize Xiao Zhan won last year, a tower undulating with three diminishing spheres.

“Your award,” Yibo says, barely able to rasp out the words. “You could fuck me with your award, since you can’t do it yourself.”

Xiao Zhan’s hand on him goes brutally tight, almost painful, and he sucks harder before lifting his head. His lips are slick when they brush Yibo’s ear, his breath warm and panting.

“Maybe that’s all you’ll get,” Xiao Zhan whispers. “Unless you beg for it.”

“Yes, Xiao-jiaoshou,” Yibo breathes, immediately. He turns his head and kisses Xiao Zhan hungrily. “Please fuck me. Put your dick inside me. I want to make it good for you, I’ll do anything you want...”

He’s never talked like this in his life, and his face is scalding hot, but Xiao Zhan’s thigh is so hard between his own, and his back aches being bent so far over, and it feels so, so fucking good when Xiao Zhan starts jerking him off for real, smooth and fast and perfect.

“Gonna fuck you right here over my desk,” Xiao Zhan says, gasping. “Anyone could walk in, anyone could see—”

Yibo’s not sure if that’s part of the fantasy or about what they’re doing right now, locked door or not, but the idea of a janitor or one of Xiao Zhan’s colleagues seeing them is so shamefully, blazingly hot that he has to bury his face in Xiao Zhan’s shoulder to muffle his shout as he comes, sharp and sudden and intense. Xiao Zhan keeps stroking him the whole time, squeezing the head of his cock tight, and it feels like it goes on forever, until Yibo’s choking for breath, with Xiao Zhan’s shirt clenched between his teeth and his body convulsing over and over again.

When it finally stops, his legs are completely useless, and he sits down on the desk, arms still flung around Xiao Zhan as his only support. He presses his face into Xiao Zhan’s sweaty neck and they just hold each other, gasping and wrecked, the best feeling in the world.

“I’ve never,” Xiao Zhan breathes, and then just shakes his head. He holds Yibo tighter, pressing a kiss to his temple.

Yibo’s had sex this intense before, but not with Xiao Zhan, and a grins creeps over his face. He’d been wondering if something like this was lurking under Xiao Zhan’s calm, affectionate manner in bed, and now he knows.

Slowly they calm down, sweat cooling and their breath slowing. Yibo kisses Xiao Zhan’s neck, rubbing his back, and finally gives a satisfied sigh.

“You wanna go get some dinner?” he asks, straightening up. “My treat.”

Xiao Zhan just looks at him for a moment, still a little breathless and worked up. His expression is rueful and knowing, like he’s revealed more of himself than he meant to. He runs one hand through his messy hair, smoothing it, then glances down at his crumpled shirt. Yibo raises an eyebrow, smirking.

“We can pick up,” he says. “Take it back to mine...or yours.”

He strokes Xiao Zhan’s face, cupping his jaw. It seems like Xiao Zhan’s still overwhelmed by what just happened, and Yibo wants to bring him back, make things feel more ordinary and easy. He tips his head in to rest their foreheads together, and he feels Xiao Zhan sigh, relaxing.

“Maybe you can tutor me at home,” Yibo whispers, one last irresistible dig. “You know, some extra practice. Do you give private lessons?”

Xiao Zhan’s hand comes up to close over the back of his neck, tight. “Depends on how hard you work,” Xiao Zhan says, and something warm curls through Yibo at the dark tone in his voice. “Are you serious about your grades?”

Yibo draws back, just enough to look Xiao Zhan in the eye. “I’m very serious,” he says, and then he smiles.