"Get on your knees, worm."
The sneer on Harry Potter's face left no doubt about the scorn he felt for his old Potions Master. Snape's knees thudded to the stone floor of the classroom. To be forced into this situation was beyond humiliating. But what choice did he have? Dumbledore was dead, and now Voldemort was as well. Only Harry Potter remained, and despite all Dumbledore's praise of the boy, he had turned out just as rotten as Snape always knew he would.
The problem, Snape knew, had come when Voldemort decided to cut away at Potter's support. The Dark Lord had assumed that without his friends, Potter would be nothing more than a nuisance. It had been Voldemort's last, most critical error in judgment. Without his friends, Potter had nothing to lose, no reason to hold back. When the confrontation had finally come, when Potter had found Voldemort and his Death Eaters planning an attack on Hogwarts, Potter had singlehandedly killed half their number. Voldemort himself had fallen first, before he could even raise a wand against the man who had come to kill him, the man whose heart now contained room for nothing but hatred and vengeance. Oh, how wrong Dumbledore had been.
"Will you swear to serve me, Severus?"
What pleasure he seemed to get at this. Bile rose in Snape's throat and he fought the urge to vomit. He bowed his head and stared at the stone floor below him. "Ye-... Yes. I will serve." And survive. And perhaps some day find a way to rid the world of Harry bloody Potter. The thought was all that kept him going.
Potter's left hand whipped out, snakelike, and took hold of Snape's hair, pulling his head up. "Then serve, Snivellus. Serve where you have always belonged: on your knees." His right hand unzipped the fly to his trousers.