Written for a forum prompt: "They've been together for ages now but Severus still can't bring himself to ask Harry to submit to him the way that he wants, not with their rocky history. Harry knows that Severus is holding back from something, there's a distance between them that hasn't been there for years, but when he deliberately pushes his lover over the edge he's surprised at just how intense things get."

"I'm not getting any younger . . ."

Harry stuck his head through the doorway and shot his husband a smirk. "Obviously, old man."

"Fifty isn't that old."

"Older than you were yesterday. Happy birthday, Severus. I'll be there in a minute."

Severus sighed and tried to focus on his book. He had been sitting here on the bed, pretending to read, for twenty minutes now. Not actually taking in a single word. He would have suspected Harry of dawdling, but that really wasn't Harry's style - after all their years together, Severus felt confident in stating that waiting was not Harry's strong suit. Something he took advantage of on a fairly regular basis, actually, but still . . .

"Are you avoiding me?"

"No, sir." Harry's response was immediate. Also learned over all their years together. "Just getting things ready for your birthday present."

Severus felt his cock stir. Harry knew he despised birthdays, especially his own, and he particularly despised the insipid kinds of gifts people usually got each other for the occasion. Several years back, Harry had hit on a "gift" Severus found much more palatable - once a year, Harry got to choose the direction of their play for the evening. He was amazingly creative, frighteningly astute at guessing what perversions Severus might like but not have tried yet, and particularly open about his appreciation of Severus's erotic talents. It had taken them a long time to shape their current relationship - Severus usually directing, Harry usually following, both with vast emotional minefields to navigate. It was years before they had even broached the subject of Harry's time at the Dursleys, or Severus's experiences with the Death Eaters. They fell into their respective dominant/submissive roles easily, all things considered, but that didn't mean Severus had free reign to try everything. He sighed. It was an old regret, something quickly pushed aside because of his love for Harry, but -

"Okay, Severus, I need you."

Severus pushed himself up off the bed and carefully marked his place in his book before placing it on the nightstand. Making Harry wait. His skin felt alive with anticipation as he exited the bedroom and walked into the sitting room.

And stopped dead. Harry really had been busy - the room looked nothing like it normally did. The walls had been transformed to dark stone, the usually cheery wall sconces to flickering candlelight, and the coffee table to -

"It looks like my classroom was at Hogwarts," Severus said. "You've transfigured it all like - it's my classroom."

"Yes, Professor." Harry stepped out from behind a shelf of potion ingredients and stopped, allowing Severus to inspect his attire.

"What do you think?" he asked with a little smile. "Turns out it still fits, no adjustment charms needed."

Severus just stared. Harry stood before him in his school robes, Gryffindor crest and red-and-gold striped tie and all. He had even charmed his hair to stick up in that infuriating way it always had when he was a student.

"I seem to be having some trouble with my potions assignment, Professor," Harry said, indicating to the cauldron on the coffee-table-turned-workbench in the center of the room. "I was sure you said to stir three times, but I must not be very good at following directions. It's not changing color. I really would rather not have to serve detention, sir."

Severus blinked at him, still trying to take it all in. Harry cocked his head to the side and waited for his husband to catch up, but Severus just couldn't make the last leap.

"I know you want this," Harry finally said softly, taking Severus's hand. "You wanted to spank me back then and you want to spank me now. For different reasons, I hope," he added with a hint of a smirk, but then sobered. "I've submitted to you in every other way - I trust you."

Severus dragged in a deep breath. "Of course I'd love to . . . I just don't . . . I can't ask this, Harry," he said. "Not after what your uncle did to you. No matter how much I want to try everything with you, I'm not going to ask this. I can't."

Harry reached up and dragged Severus's head down for a brief but passionate kiss. "I. Love. You. You're not asking; I'm offering."

Severus closed his eyes. "I can't."

"Okay. Be creative, then. Find something else."

Severus opened his eyes again, just in time to see Harry's expression change. Harry ducked his head a bit, adopting the bad posture he habitually had at seventeen, and worried the corner of his lip in a way Severus now found absolutely delightful but at the time had driven him wild with annoyance. Harry shuffled over to the workbench and prodded the cauldron again.

"It's bubbling, Professor. Is it supposed to do that? It's not even over a flame. Should I add powdered Erumpent horn to cool it down?"

Severus choked back a laugh. Harry was really pulling out all the stops - if Severus wouldn't punish him for an imagined reason, maybe he'd punish him for deliberately bolloxing up his potion, perhaps? Disrespecting the art of potion-making as a whole?

Harry wandered over to the cabinet of ingredients (formerly a bookshelf) and pulled out a jar which was, indeed, labeled "Erumpent horn." Severus doubted Harry would be stupid enough to actually transfigure something into such an explosive substance in their own sitting room, but then Harry was capable of being tremendously stupid in the pursuit of Gryffindor "bravery" . . .

And just like that, Severus was interested. He flicked his wand twice: the first to banish the jar from Harry's hand, and the second to knock Harry back against the workbench. He didn't miss the flare of heat in Harry's eyes before Harry adopted his student mask once more.

"Professor?"

Severus muttered a spell under his breath, transforming his own robes to the severe black he had always worn at Hogwarts. Harry's eyes definitely flared now.

"You," Severus intoned in his most terror-inflicting professorial voice, "are the most addle-witted student I have ever had the misfortune to teach, Mr. Potter."

Harry gulped.

Severus stalked closer, stopping only when he was looming over Harry and glaring down into those vivid green eyes. "You're an embarrassment to Hogwarts," he hissed, "and to the wizarding world as a whole. And especially to my potions class."

"Y - yes, Professor." Harry blinked up at him, eyes wide. "I'm sorry, sir."

"Don't be sorry," Severus snapped. "Be mortified. Be profoundly embarrassed that you haven't grasped a concept as simple as the difference between clockwise and counter-clockwise. Be humiliated that you are making a mockery of my entire profession."

Harry's tongue darted out to moisten his lips. "Am I - am I in trouble, sir?"

"That depends," Severus said, narrowing his eyes. "Let's see how badly your potion went wrong, shall we? Close your eyes."

The ever-obedient Harry did as he was told, although his Adam's apple jumped as he did so. Severus leaned over to peer into the cauldron - no telling what Harry had in there, honestly, could be a real potion or just a mess of ingredients, but the important thing wasn't the potion. Although . . .

Severus performed several wordless spells in quick succession. One to tip the unidentified mess out of the cauldron and into a summoned flask, another to stopper it and cast a magical stasis spell on it (just in case Harry did, in fact, make something dangerous) and banish it to sit in the bathroom sink, and another to summon a bottle from Severus's private potions workshop at the other end of the house. Severus took the bottle, tipped it into the cauldron (making sure to scourgio it thoroughly first), then adjusted the color and viscosity so it roughly approximated the whatever-it-was Harry had created. It wasn't perfect, but it would do.

"Sir?"

Severus picked up the cauldron and pressed it into Harry's hands. "Drink."

"I -"

"Now, Mr. Potter."

Harry took a deep breath and upended the cauldron into his mouth. He shuddered and grimaced, but he kept going until the entire bottle's worth of potion was down his throat.

"You may open your eyes, but do not speak unless I ask you a question. Do you understand, Mr. Potter?"

Harry's eyes popped open and he nodded.

"That was a question, Potter."

"Yes sir." Harry reached up to rub his throat. "That burned, Professor. What -"

Severus's hand shot out, catching Harry under the chin and effectively shutting his mouth. "Only. When. Asked. You are in serious trouble right now, Mr. Potter, do you understand? Nod your head yes."

Harry nodded again.

"Here is another question: do you know what happens to an awareness potion when you stir it clockwise instead of counterclockwise in the penultimate step?"

"Ah, no sir."

"You will." Severus smirked, enjoying the not-entirely-faked look of trepidation on Harry's face. "As you will soon be discovering, the difference between clockwise and counterclockwise affects whether the potion augments vision and hearing or . . . other senses." He reached up and ran a long finger roughly down the column of Harry's neck. Harry only just barely suppressed his shiver. "You skin should be getting extraordinarily sensitive right now, Mr. Potter. Is it?"

Harry closed his eyes and let out a sharp pant. "Yes - yes sir, Professor Snape."

"Excellent." Severus retreated a step and took a moment to enjoy the sight of Harry struggling to adjust to the new sensations. "I hope you understand that your detention will be immediate. I would hate to waste the opportunity."

"S - sir?"

Severus slapped his cheek, lighter than usual because of the potion, but Harry let out an obscene moan anyway. "I did warn you not to speak, Mr. Potter." Severus stalked around Harry a few times, taking in his body from every angle. "How do your clothes feel?" he asked.

"Itchy," Harry mumbled. "Too much - too rough -"

"You should have thought of that before you chose to disobey in my class," Severus whispered in Harry's ear. And then, on a whim, caught and bit Harry's earlobe, causing him to absolutely writhe. Oh, this was excellent. And Harry was staying obediently silent. Even better.

"Much as I'd like to be hands-on for this, I think a more nuanced detention is in order. Retrieve your cauldron please, Mr. Potter."

Harry opened his eyes - his pupils blown wide with arousal - and picked up the small cauldron.

"Clean it."

Harry reached for his wand, sitting on the workbench, but Severus stopped him.

"No magic. Use your tongue."

Harry's mouth dropped open. The expression probably started in surprise, but Severus kept his best potions professor glare on his husband and Harry's gesture turned into a gradual intake of breath. He slowly drew the cauldron to his mouth and gave the inside rim a long lick.

"All of it, Mr. Potter."

Severus retreated to sit at his desk (Harry had transfigured their little writing table to a reasonable approximation of the desk in his classroom, Severus noted) and sat to watch Harry work. The cauldron wasn't large, but awareness potion tasted foul and Harry had to do some particularly interesting contortions with his tongue to reach the potion residue on the bottom. Severus palmed his erection through his robe and stroked it lazily as he watched. The potion was definitely in full effect now - Harry was squirming, itching to get away from the magically enhanced stimulation provided by his clothes. Anything touching his skin would be more intense now - it was so tempting to just give in, to give Harry the spanking he wanted -

Severus shook his head to clear it. "No spanking" was one of the rules they'd established early on, when he and Harry had first added dominance and submission to their relationship. Harry's Uncle Vernon had spanked him frequently, he had tearfully confessed during one particularly emotional encounter, and sometimes those spankings led to more. Never rape, not quite, but certainly things that no man should be doing to a child. Severus was conscious of the age difference between himself and his husband - a full generation, same as between Harry and his Uncle Vernon - and so spanking had stayed firmly off the table.

That didn't mean Severus didn't miss it, though. Spanking was easily his favorite not-actually-sexual activity. Not that he had been able to indulge it all that much before his relationship with Harry, but still. Something about the thought of Harry's gorgeous ass in the air, cherry-red and oh-so-sensitive under his palm . . . Severus shifted in his seat. Harry was a generous lover and an excellent submissive. His kinks happened to align with Severus's particularly well, most of the time. And if the price was giving up spanking, Severus would pay it gladly.

The clunk of the cauldron being set on the workbench drew Severus's attention back to Harry. He was very definitely in subspace now, his eyes dark and his breathing quick. If Severus had known this aborted awareness potion would be so interesting, he might have made some ages ago. As it was, he'd only had a bottle in his workshop this evening because he'd gotten distracted by Harry the week before and accidentally made the same clockwise/counterclockwise mistake he was pretending to punish Harry for. And then decided perhaps the potion might have uses in its current form as well. Time for another step.

"Is it clean, Mr. Potter?" he asked in a deceptively pleasant voice, the one that never failed to give Harry goosebumps.

"Yes, sir," Harry answered shakily.

"Excellent." Severus stood, rolling his shoulders to ease the tension. "Clothes off, please."

"Sir?" Harry was biting his lip again, clear evidence he was just feigning surprise. The sight went straight to Severus's cock anyway.

"All of them, Potter. What did I say about talking?"

Harry dropped his head and immediately went to work on his robe. "You told me not to talk unless directly asked a question, sir." He gave a little shiver as he worked the robe off his arms and let it fall to the floor, then started on his tie and shirt. "I'm sorry, sir."

"Quickly, please. I have a perfectly good book I'd like to get back to when we're done here."

A few more wriggles later and Harry was standing naked before him. Very definitely aroused. Severus took a moment to look him over - he never got tired of seeing his husband's body. Harry kept fit, evidence of his career as an auror, and even the occasional scars he'd acquired over the course of his career only added color and character to his magnificent physique.

"Feel better without your clothes, Mr. Potter?"

"Much, sir."

Severus shot him that placidly pleasant smile again. "That's rather unfortunate. The purpose of detention is not to feel better, Potter. Accio rope!"

Several coils of rope flew from the wardrobe in the bedroom and into Severus's outstretched hand. It was easier to bind with magic, of course, but for this purpose, Severus preferred a more tactile approach. Especially when Harry was so sensitive . . .

Harry stood almost perfectly still while Severus worked, little shudders and flickers his only concession to the potion when Severus's fingers touched him. This was one of their favorite things - Severus adored thinking of new ways to tie up Harry, and Harry adored being tied up. Severus had been mulling over a particularly intriguing option for a week now, trying to get it all perfect in his head before he surprised Harry, but tonight was a good a time as any. Especially while Harry was sucking in his breath every time Severus's fingers brushed his skin.

It took several minutes to do, but Severus was quite pleased with the result. He stepped back, holding Harry by the elbow to turn him this way and that so he could admire his handiwork. Both feet were thoroughly wrapped, so Harry was stepping on a tight cushion of rope every time he moved. Severus had also pressed Harry's wand into service, tying it horizontally across his waist so it moved when he breathed. The ropes from his feet led upward, fed over the center of the wand, then backtracked to trace through his legs and through the cleft between his cheeks all the way up across his back, curling over his shoulders and ending at his chest where Severus had transfigured the ends into nipple clamps. Severus cinched the ropes tight, forcing Harry to stoop a bit - every time he took a step, the rope would glide over his sensitive entrance and tug on his nipple at the same time. If Harry tried to stand up straight, the pain would be incredible, even without the awareness potion. Severus cast one final spell on the rear section of the rope, slicking it down and making it whisper-soft so it wouldn't abrade Harry too badly. It would do.

He could tell the exact moment Harry figured out the ingenuity of his plan: Harry went from pleasantly semi-stiff to hard as a rock immediately when Severus removed the slack in the rope. Despite the orders not to speak, Harry let out a plaintive whine.

"You may talk to me now, Mr. Potter," Severus conceded lazily. "But only to tell me now it feels."

"Bloody amazing," Harry gasped. "It hurts so much, and yet . . . oh God!"

"'Professor' or 'sir' will do," Severus replied dryly. "Now for the more useful portion of your detention . . . I notice that the potions cupboard is a bit dusty, Mr. Potter, wouldn't you agree?"

Harry glanced over at the perfectly pristine shelves, which until recently had held mostly books, but he nodded anyway. "Yes, sir."

"I am trusting that even such an embarrassment to Hogwarts such as yourself could manage to dust some shelves, Potter. You will remove the contents of the potions cupboard, one at a time, and place them in alphabetical order on the workbench. You will then come to me for a cleaning rag and you will wipe down the shelves and each of the bottles. Do you understand?"

Harry squirmed a bit against the ropes, but he nodded again. "Yes, sir."

"Good. I'll be at my desk; I expect not to be disturbed." Severus returned to the chair at his transfigured desk, summoning the book from the bedside table on his way. He propped his feet up (something he had almost never done while actually teaching, but feigning nonchalance seemed appropriate now) and opened to the page with the bookmark.

He didn't actually manage to read any better than he had in the bedroom, of course. Even though he kept his eyes firmly on the pages in front of him, Severus's entire awareness was taken up with the beautiful noises Harry was making as he walked back and forth the half-dozen steps from the shelves to the workbench. Harry was breathing heavily, practically whimpering as he moved. His cock was hard as a pike, straining outward and glistening at the tip, but Harry was used to Severus's whims by now and knew to ignore it. As best he could, anyway. Severus shifted in his chair, trying to ignore his own erection, but it was bloody impossible with Harry looking so completely fuckable not fifteen feet away.

The crash was perhaps inevitable. It took only a few minutes for Harry's tiny whimpers to work their way to fully-fledged moans of desire, which did absolutely nothing for Severus's self-control. Harry's thighs must have been aching by that point, holding himself in a half-crouch as he walked back and forth, but when he could finally stand it no longer and straightened them, the sounds which came from his mouth took on a wholly new and delightful tone as the rope pulled painfully on his nipples. His startled cry was punctuated by crashing glass - the bottle of lavender essence shattered on the stone floor. Harry looked up at his husband, hope and fear and lust all warring on his face.

All Severus's promises to himself vanished at that instant. Harry had asked - begged, damn it! Severus jumped to his feet, collected himself a tiny bit, and merely stalked rather than ran to Harry's side.

"You broke my bottle, Mr. Potter."

Harry gulped and whimpered.

"I see an alternate punishment may be in order after all," Severus drawled in his his most menacing tone, the one that made Harry light-headed more often than not. "Bend over my desk, Potter, hands on the opposite edge."

Harry's eyes flew to his. "Sir?" he whispered.

"Now, Mr. Potter."

Harry swallowed hard, but ducked his head and darted past Severus to the desk. He leaned over the heavy wood, front half flat over the desktop with his fingertips just able to curl around the lip on the other side. His ass was presented to Severus in full glory, the twin ropes straining over his back and undoubtedly pulling something terrible at the nipple clamps. Severus had never seen such an erotic offering. He meandered closer, admiring, then darted a hand out to grab the ropes running along Harry's spine and insinuate two long fingers underneath it.

He pulled gently, putting an inch or two of air between the ropes and Harry's back, and Harry choked out something which could have been "please" and could have been in another language entirely, something never before heard by wizard or muggle. Severus played a few moments longer, sliding the rope past Harry's hole and tugging on the clamps again and again until Harry was completely incoherent. Eventually he had to stop, though, if he wanted to do this right . . .

"You've been misbehaving, Potter," Severus said again quietly. "I think a spanking is in order, don't you?"

"Oh, yes, sir!" Harry exclaimed with a twitch of his hips which was somewhere between a shimmy and a writhe. "I have been bad, sir."

"And will a spanking help solve the problem?" Severus slid his free hand down Harry's hip and over his backside, massaging the skin there. Harry's breathing hitched again. "I need you to tell me when you're ready, Harry."

"I'm ready," Harry whispered. "So, so ready."

"And if you say stop, I'm stopping, no questions asked."

"Just do it, Severus. Spank me. Sir. Professor. Oh fuck oh fuck oh -"

Smack. Severus brought his hand down without any more preamble, leaving a satisfying sting in his palm and immediately cutting off the flow of Harry's words. Harry was panting, little breathy sounds.

"That was one."

"One," Harry mumbled.

"Good." Smack. "That was two."

"Oh fuck oh god - two, two!"

Severus aimed a bit lower for the next few, then back up for the one after that, working his way across Harry's delectable ass. Harry panted and squirmed and swore and counted every single smack. On ten Severus gave the rope a sharp tug just as his hand connected, and Harry flew apart even without anything touching his cock. He screamed and stiffened, then went boneless against the desk. Severus couldn't hold back any longer - he vanished his robes and had his erection in his palm in seconds, and barely half a dozen strokes later he was coming in a silky burst across Harry's abused form. Harry gave a half-hearted wriggle, acknowledging, but didn't comment when Severus collapsed onto the desk next to him.

They rested like that for a handful of minutes, neither moving, before Severus finally groaned and forced himself to his feet. He vanished the ropes from Harry's body, replacing them instead with soothing hands and kisses. "How do you feel?" he asked.

"Bloody brilliant," came the slurred reply. "That was 'xactly what I needed. Thanks, Sev'rus."

"Come to bed?"

Harry mumbled something, but hauled himself upright. He turned, then stopped and blinked at the mess in the middle of the room.

"Leave it - we can clean it up later."

"Later."

Severus tucked his arm under Harry's and together they headed back to the bedroom. There was still a long night ahead of them.