Author's Note: Wrote this for my best friend's birthday. I love this pairing, and personally, I think there isn't enough of it. Enjoy!
Severus stalked into his office and found Sirius Black, hands aloft in surrender, expression filled with confidence even covered in dirt with matted hair. "You are insane," he drawled, "to not only come to the Castle, but my office." He pointed his wand at the brunet. "I should summon the Dementors."
"Well, beside from the fact the Headmaster doesn't want them in the Castle, you do have another choice," he remarked, shifting the raven's wrist enough that he was out hex range.
"You mean aside from dragging you out of the Castle?" he purred dangerously.
Sirius grinned and shifted closer by a few inches. "Don't tell me you're not tempted to take your revenge," he remarked with a wicked grin.
The Potions Master smirked. "I do not think you would enjoy it."
Sirius' expression turned earnest. "I deserve to be punished for what I did to you, and who better to exact it, than you? Don't you want to take it, be the aggressor for once?" he spoke, voice temptation personified.
"Do you really think I want to touch you?" he drawled disdainfully.
The brunet's grin turned rueful. "I realise I'm not at my best, but surely you can't pass up the chance to have me bent over a desk at your mercy?" he asked, almost able to keep the breathiness out of his voice.
Severus regarded him for a moment and flicked his wand. "Ow!" Sirius complained when his skin was suddenly scrubbed clean. "Don't do that with my hair," he begged, hands going to it protectively. The raven chuckled and flicked his wand again. The brunet's hair became clean and untangled.
"Better," he stated, threading his fingers through Sirius' curls and tightened to just this side of pain. The Animagus let out a breathy moan. "I never heard about this side of your exploits," he murmured.
"And give my bed partners power over me?" he retorted. "They were brief dalliances, nothing more."
Severus shook his head and flicked his wand several times. Two potion vials floated over to them. "Drink those," he ordered. "I have no desire to bed someone so emaciated." Sirius took them quickly. "I am amazed you took them without vows on my part."
"Well, if you gave me something horrible, I'd deserve it," he replied. He grinned. "You can't blame me for hoping for something more pleasant though." The raven flicked his wand and Sirius' clothes disappeared. "Inspecting the goods?"
"Those rags are vile," he replied, though his eyes did flick over the brunet's frame. With a smirk he used his grip to turn Sirius around and bend him over the desk. The Animagus' breath sped. "So eager already," he drawled, shaking his head before he undressed himself with a flick of his wand. "Neither of us wants any accidents," he remarked and cast a contraceptive charm, then cast a cleaning charm. "I am not cruel," he stated and cast a lubrication charm, "but I am not going to stretch you. You are going to feel every inch."
Sirius let out a shaky breath. "I deserve it," he stated.
Severus released his hold on Sirius' hair and pressed the head of his cock against the brunet's entrance. Sirius let out a breathy moan. "I certainly never heard about this," he drawled.
"I was always the top," he stated, "I wasn't going to give them that kind of power over me." He turned enough to lock gazes with the raven over his shoulder. "Letting you know my deepest, darkest desires is the least I can do as penance."
Severus threaded his fingers in Sirius' curls and tightened until the Animagus moaned. "By the time I am through with you, you are going to be feeling me for days," he purred dangerously.
"Promises, promises," he replied breathily. Severus tugged Sirius up and into a heated, possessive kiss.