Sirius practically skipped down the hall whistling a merry tune, the familiar sight of Bertrand the Barmy enough to fill him with a disconcerting amount of glee.

Sirius eagerly awaited the end of the week, as much as any other teenager. But ever since Severus Snape had become a part of his Friday routine, the anticipation seemed even greater. Too often he found himself counting the seconds to 7:00, his mind reliving visions of pale skin, jutting hipbones, and greasy hair.

Intellectually he found the situation with Snape beyond disturbing. If Remus or James ever found out, he'd certainly be carted of to St. Mungo's. But Sirius had no intention of stopping. Beyond logic, beyond reason, his current affair was too euphoric to stop.

Besides, if Sirius didn't put Snape in his place, who would? Really this should count as a public service.

He entered the classroom and his lips twitched downwards when he discovered it was empty, save for Snape's ratty corduroy satchel. Sirius sighed and plopped next to the bag, disgusted with himself to feel so disappointed by a room's lack-of-Snape.

The seconds passed by and Sirius couldn't help but stare at the shabby school bag. Why on earth would Snape leave it lying around? There was no doubt it belonged to him, Snape had a very singular bag. He knew of only one individual with a bag that frayed, and stained, and violently orange.

He felt strange though, almost drawn to it. It was hard not to be, with a color like that, but something was off. The longer he looked, the more he felt a compulsion, not to look at the bag, but look in it.

He placed it on his lap, and gently opened the flap to peer inside. Next to the heavy schoolbooks he saw a brightly colored package.

Pick it up.

It drew him in, and before he knew it, he was handling a large box of Honeydukes' Premium Chocolate Truffles. Snape's schoolbag lay forgotten on the floor.

Eat one.

It was true, Honeydukes' Premium Chocolate Truffles were his absolute favorite, not only that but he usually only indulged once a year at Christmas time. But he couldn't. Surely not. Snape would certainly throw a tantrum if he ate one.

Who cares about what Snivellus will think? And besides, the box is open. He wouldn't miss just one.

It was true the box was open. A few of the precious confections already eaten. The brightly colored chocolates smelled so rich. Seven candies, all different colors, Galleon sized. Surely Snape wouldn't miss just one. Sirius picked the pink one up and held it in his hand. White chocolate and Strawberry, his favorite flavor. It smelled divine.

Go on. What are you waiting for? Eat the truffle.

With out a second thought Sirius gobbled the treat, his mouth filling with the sweet flavor. Honeydukes really did make the best chocolates. But, as the smooth taste of chocolate and strawberries disappeared, a pungent aftertaste was left creeping onto his palate.

Sirius made a face, smacking his lips. It tasted vile. He jumped up from his seat, the taste so strong he began to gag. He was panicking now, trying to spit, to rub his tongue on his sleeve, but the more he tried to rid the taste from his mouth the stronger it became.

And suddenly when the putrid taste overwhelmed his senses, a wave of pain went straight to his groin.

Sirius screamed and collapsed on the floor. Writhing as he felt his nether regions burn. The pain so overwhelming he thought he might pass out. He was unsure how long he thrashed about. But when the pain ceased and his wits returned, the sight before him was most unwelcome.

"Good evening Black."

Sirius looked up, vision still whirling from pain. Severus Snape towered over him, looking down with smug satisfaction.

"Didn't your mother ever teach you manners?" Snape held the truffle box in his hand, studying it intently, "It is very rude to root through someone's bag, and even ruder to steal their things. You've been such a naughty boy today, I'm ashamed."

The look of superiority on his enemies' face was infuriating. Sirius ground his teeth. He tried to stand, but his knees buckled under his weight and he crashed to the floor once more. Movements slow and limbs heavy.

"You- you- you just wait until I get off this floor I'm going to…"

Severus clicked his tongue in mock disappointment. "Temper, temper. Well Black, I won't hold my breath on that happening anytime soon. We both know what you came here to do. Unfortunately I think you'll find it quite difficult today. Given the… state of things." He gestured downwards with a slim finger silently mouthing the words, "Down there."

Sirius felt cold creep into his veins as he caught on to Severus' insinuation.

"What the fuck did you do to me you bastard?"

"Why, if I told you now it would ruin the surprise."

Sirius panicked, struggling to undo his zipper. He shoved a shaking hand down his pants, his eyes widening when he discovered what used to be a source of pride was now…

"What's the matter Black? Smaller than you're used too?"

Black's heart felt like it would burst from his chest. He clumsily shoved down his trousers and pants, his need to see for himself exactly what happened outweighing his modesty. He instantly regretted his actions though when Snape began laughing so hard he had to hold onto a desk for support. Sirius felt his whole body flush as he looked down. His once proud cock was now barely an inch long and his balls shriveled to practically nothing.

"WHAT IS THIS SUPPOSED TO BE?!

Severus wiped the tears from his eyes. "Funny Black, that's exactly what I was going to ask you."

"You bas-" Sirius tried to lunge forward again, but his legs were still two weak to hold his weight. He sat on the floor, shaking with rage.

Severus straightened himself and took a hold of Black's chin, lifting it firmly to look up and meet his eyes. When he spoke his voice was dangerously soft. "You know Black, there is a certain potion. It shrivels you up to nothing and the best part is it is irreversible. No antidote, no incantation, no healing procedure will ever return you to your original size. When one consumes this potion, it is tasteless, but soon the recipient begins to notice a bad taste in their mouth. A taste, no matter how desperately they try, they can't get rid of. They try and try and try and are so relieved when the taste disappears. But then the burning starts. Down. There."

Black eyes widened in fear, "You didn't…"

Severus gave twisted grin, baring his crooked teeth. Black felt faint. No. No. This couldn't be happening. Anything but that. Anything. Severus let go of his chin and turned to walk away. Leaving Black on the floor close to tears.

"Lucky for you Black, your situation is reversible. But you'll have to be a good boy and follow my instructions very carefully."

Sirius perked up, desperate to rectify this situation. Severus continued, eyeing one of the chocolates once more.

"You see I was the one who invented this potion. I invented it just for you! Think of it as a gift. I even created an antidote. Aren't I just so thoughtful."

He sat the truffle back down in the box. Long, slender fingers trailing the flat surface of the teacher's desk.

"I wouldn't have bothered putting in such time and effort, but it came to my attention during our last few meetings you don't know the difference between boys and girls. So I thought I'd do you a favor and teach you. I came up with this potion as an effective teaching tool, to help you pay attention to the lesson."

Severus walked round and stood in front of the ornate teachers chair, and began to undo his belt.

"Lesson one. You see Black, men have a penis. I am a male. I have a penis. This is what a penis looks like."

Sirius' eyes widened as Snape dropped his trousers and pants. Kicking them to the side. Revealing a modest sized package, fully erect. Severus smiled down at Sirius' scandalized expression.

"Which brings us to lesson number two. A penis produces ejaculate. Lucky for you I've ensured to become a man again you have to learn THIS lesson intimately."

Severus lowered himself onto the chair, slowly running his hand up and down the length.

"That's right Black. The antidote is my cum. Not just anyone's cum. Mine. So if you want your cock back, you are going to crawl over between my legs and suck my cock until I cum down your pretty little throat. I suggest you spend this time thinking about the difference between girls and boys, and what MY gender is."

Sirius twitched from his place on the floor. As if he would ever cave to such demands. He struggled with his zipper, forced again to look at how shriveled and pathetic his cock was. He felt the heat of cheeks and neck as reddened even more as he hid his shame. He tried to stand, but fell yet again.

"Why can't I stand up? Let me go!"

"Another side effect of your gift I'm afraid. Can't have you skiving off such an important lesson."

Sirius felt the rage boil in his stomach at the injustice of it all. He looked up at Snape as something dawned on him.

"You did this to me! You made me eat those chocolates. There was some sort of compulsion spell wasn't there?"

"Ah yes… but again, given the gravity of the subject I'd say it was justified," While Sirius sputtered on the floor, Snape smiled and raised a hand, beckoning Sirius to come sit before him with a single finger, "Enough blithering Black. Now if you want your faculties to return I'd crawl over here and get to work."

Sirius assessed his trembling limbs, unfortunately he'd have to comply. He weakly crawled between Snape's legs, the flagstones cold and rough on his palms. Once he arrived at his destination he looked up. Snape was towering over him chin in the air, looking down his nose like a king might look at a peasant.

Sirius grimaced while assessing Severus' cock. It was a similar length to his own, only shorter by maybe an inch, but was much thinner. He was consumed with rage and disgust. There was no way he could do this, but then again if the choice was sucking dick, or having no dick…

"That's it Black. Be a good boy and lick it."

Sirius gulped. Lifting a shaky hand to hold the cock steady. He leaned forward, eyes closed and tongue extended. The first contact of Snape's hardness to his tongue was horrid. A shock ran through his body as the reality overwhelmed him. He really was about to suck Snape's cock.

He looked up and saw Snape's face, full of excitement. Severus' expression did nothing to abate his anger. Sirius snarled and licked the cock again, before wrapping his lips around the head and lowering down on the length. As the appendage filled his mouth he looked deep into Snape's eyes, deliberately placing slight pressure with his teeth.

Severus inhaled sharply. The light bite wasn't nearly enough to hurt him, but the message was clear. Severus' responded in turn with his own warning.

"I'd rethink that if I were you. It would be a shame if I could no longer make the antidote."

Sirius opened his mouth wider, taking care to move his teeth out of the way, and descended on the length. He needed to get this over with as quickly as possible. Knowing Snape had never done this before he was more than likely a quick shot. Racking his brain for the techniques his previous conquests used on him, Sirius wrapped a hand around the base and began to move his mouth and hand up and down in tandem.

"Fuck."

Snape was panting. As much as he despised the circumstances, sucking cock wasn't nearly as awful as it could have been. He tried to block out the feeling of abject humiliation and concentrate on the task at hand. As expected it only took a few well-timed licks, and sucks and jerks before he felt a strong burst of warm fluid shoot into his mouth.

The force of orgasm surprised him, and he coughed up most of the cum. Spitting white over Snape's thighs and chair. He looked up at Snape furious and swallowed what was left in his mouth, cum dribbling down his chin.

"That's right Black. Drink up. You left some behind, you want to make sure to lap up every drop."

Severus panted coming down from the high. He watched Sirius on his hands and knees desperately licking every droplet of cum from the grooves of the flagstones. The sight of his desperate yet disgusted expression going straight to his groin.

Sirius finished licking up the last of the awful tasting fluid, so acrid and bitter. Shoving a hand down his pants to check on the state of his nether region caused his eyebrows to shoot up in alarm.

"Why didn't it work?"

Severus looked bored, eyes focused on the clock in the corner instead of the pathetic Gryffindor between his legs.

"I didn't specify the necessary dosage."

"What does that mean?!"

"It means Black, you're going to have to do it again."

Sirius couldn't believe his ears. He would have to do that again?! He looked at the floor. The sight of Snape's holey black socks rolled loosely over his tiny ankles filling him with fury. This was… unacceptable, but what choice did he have. He made a throaty noise before grabbing Snape's cock, more aggressively than before, and went back to sucking.

"Fuck."

Sirius' ministrations were practically business like. Forcefully bobbing up and down, channeling all of his rage into his actions.

"How does it feel Black? How does it feel to suck cock? To suck a man's cock?"

Sirius could think of a number of adjectives, humiliating, infuriating, disgusting. Sirius sneered, or at least as well as he could with a mouth full of cock, maybe it would be better if Snape showered more than his hair would suggest…

As the time ticked by his jaw began to ache, and he withdrew the length completely, opening and closing his mouth to stretch the muscle.

"Aw, is your mouth getting tired. Poor you. You have to work harder for it this time, but I'm sure it will pay off in the end. Learning such a valuable lesson. Maybe I'll give you an O."

Sirius sneered and went back to sucking, trying to hurry this travesty along.

"I should message the ministry. Let everyone know Sirius Black could earn a NEWT in cock sucking."

Sirius made an angry noise, trying to ignore the jibes. Taking the cock as deep as he could.

"Fuck yes Black you're pretty mouth is so good on my cock."

Fuck Snape. Fuck Snape and his stupid cock. And his stupid potions. And his stupid pranks.

"You love the taste don't you."

The taste was horrendous. The salty smell from the fine curls at the base making Sirius want to vomit.

"You love the taste of MAN pouring down your fucking throat."

Sirius felt Snape's orgasm build, Snape's lower abdomen tightening in anticipation as his hips began to buck to meet Sirius' mouth.

"Fuck yes. Fuck."

Severus' climaxed a second time, this time Sirius was prepared, swallowing it all with out spilling any. He withdrew the softening member, licking the last of the fluid from his lips.

Severus was panting in the chair. Languidly reaching for his wand on the desk to summon his trousers and pants. He stood began to dress himself. Putting the pants on first and then moving to the trousers. He was tying up his shoes when it came.

"Hey what the hell?!"

Severus straightened up and looked down at the pathetic cock slut lying on the flagstones. Sirius' eyes widened in anger and fear.

"What's the matter this time Black?"

"It… why? Why isn't it back."

Severus couldn't help it. He started to laugh, loudly, the timber of his voice enveloping the stone chamber. Sirius still unable to stand with out falling.

"This isn't funny! Why isn't it back. You told me it would come back! You have to hold up your end of the bargain Snape."

Snape wiped his eyes at the familiar words, this was even better than expected. He leaned against the teachers desk and looked at the clock again.

"I can't believe you believed all that Black! Really… cum as an antidote… no wonder you didn't pass your OWL."

"So… so… what?" Sirius sputtered on the floor. Panicking again. Snape smirked down at him.

"Not to worry Black. Not to worry. Ten more minutes and you should be right as rain… to walk. Your little friend should grow to full size in another hour."

Sirius felt the flush of anger creep up his cheeks and Severus walked to the door.

"I hope this was an effective lesson. See you next week boy."

And with that Severus stalked out of the room, leaving Sirius Black shaking with anger on the floor of the empty classroom.

Severus entered the Slytherin common room a large smile on his face. That had been even more amusing than anticipated! To think he got Black to suck his dick not once but twice. Walking into his dorm though he was met with quite the surprise. Along with his four room mates were ten other boys, laughing and drinking and singing loudly.

"SNAPE! Where the fuck have you been mate?" Mulciber bounded over to him, slinging a burly arm around his shoulder.

Severus stiffened at the touch. Not waiting for an answer Avery came over too punching his shoulder. "You missed it mate. You missed it! We're celebrating! We just got word. It'll be in the papers tomorrow.

Severus was suddenly much more interested. "What will be in the papers Avery."

"Victory mate! Victory!"

As the boys recounted their tale Severus eyes glittered in excitement.

And to think he thought tonight couldn't get any better.

A/N Awww aren't our boys so cute. Being so terrible to each other. I hope you all enjoyed Severus' revenge I know I certainly did ;) Thanks again for reading! And the reviews are super duper appreciated and inspiring. You all rock!