Snape permitted his fangs to descend. He stood behind Harry and wrapped an arm possessively around his chest. Harry leaned back against him and tilted his head, seductively displaying his bare neck. His skin was so near, so near and so thin, and Snape could smell the sweet blood pumping beneath. He bowed his head and pressed his lips to the flesh. He tasted the salty skin with his tongue. He dragged the tips of his fangs up and down the side of Harry’s neck, merely grazing the skin.
When he could stand to tease himself no longer, he uttered a short growl and pulled Harry roughly to him as he sank his fangs in, breaking and marking the skin and letting Harry’s blood seep into his mouth and caress over his tongue. One of Snape’s hands rested over Harry’s heart, feeling it beat as it pumped Harry’s blood throughout his body. Harry made a tender moan as he lovingly layered his own hand on top of Snape’s for a long moment.
Snape began to suck Harry’s blood from the wounds he had made, pulling it down his throat and into his being, making Harry a part of his very essence. He drank only from Harry these days, using spells to protect Harry from harm in case he ever took too much, and Snape had never felt closer to anyone in his immortal life.
Snape slid a hand down Harry’s stomach to find the bulge in his pants. He unzipped Harry’s fly and removed his cock; Snape’s bite had made it fully erect. Snape wrapped his fingers around it and Harry groaned and thrust eagerly. Snape gave him long, slow strokes as he drank him with steady swallows.
The blood had quickly made Snape’s cock hard as well. He extricated it from the layers of his outfit and pushed it against Harry’s clothed ass.
“Please, Severus,” Harry whimpered, “I need you inside, inside me while you drink.”
Loath to break the bite in order to undress Harry properly, Snape used his vampire strength to tear Harry’s clothes clean from his body with one hand. Harry moaned and wiggled his ass until Snape’s cock had slipped between his cheeks. With wandless magic Snape used a snap of his fingers to create a slick lubricant. He reached between their bodies and smoothed the lubricant over his hardness as he continued to jerk Harry languidly, then added a little to the outside of Harry’s hole. All the while Harry leaned into the bite and made soft, sweet, eager sounds.
Snape slid into him so slowly that it was torturous. Harry started whispering “please please please…” Snape could taste the desperation in his blood - just a little bit bitter, like dark chocolate, and he drank deeply.
At last Snape was fully inside. He and Harry made simultaneous sounds of pleasure and Snape quickened the pace of his hand pumping Harry’s cock. With his other hand he gripped Harry’s hip and began to pound into him with profound relief. He knew Harry felt the same; he could taste the relief in his blood like a rushing waterfall - pure and vibrant.
“Severus,” Harry called, “you feel so good, fuck me, drink me, I’m yours, I’m yours.” He rocked his hips and met Snape’s thrusts. The muscles inside his ass tensed and released around Snape’s cock, milking him. Snape growled against Harry’s neck and jerked him at speed. Harry’s cock felt hot against Snape’s cool hand, his blood felt hot flowing down Snape’s throat, and Snape felt a rush of overwhelming love, and endless need: Harry was his - his beloved, his sustenance - and that was how it should be.
Snape could taste the lust rapidly building in Harry’s blood like layer upon layer of sugar granules raining down on dewy grass, coating everything like snow. Harry was shaking and sweating and once again chanting “please please please…”, though it was release he was begging for this time, and Snape didn’t wish to deny him.
Snape gave Harry’s cock a light squeeze to signal it was time. He slammed into Harry’s ass wildly and jerked him with matched abandon, then waited for him to come first.
“Severus,” Harry moaned, and his blood tasted like a flame, rising, spreading, burning Snape with ecstasy, consuming him with ecstasy, hot, hot, so hot - and then Harry released, spilling adamantly over Snape’s hand, the taste of flame flaring beyond containment for a perfect instant, then dissipating into soft curls of candy clouds. Snape swallowed greedy mouthfuls and, with a final snap of his hips, let himself release, holding Harry’s body flush to his as he shot deep into Harry’s insides, claiming him with his cool seed, relishing his final gulps of hot blood and growling vehemently around the flesh of Harry’s neck.