"If you can come without touching yourself, Mister Potter, be my guest."
"Severus!" he cries, gripping handfuls of silken sheets until his knuckles are white. "You know I can't!"
"You know the rules."
Harry, on his knees: shirt unbuttoned, cheeks flushed, panting with desire. Snape held his chin in a steel grip, black eyes boring into green.
"Refuse me once and this is over."
Harry whimpered as his trousers grew painfully tight.
Harry whines desperately and thrusts back as hard as he can, and then - oh, god no, please not yet - Severus lets out a shuddering breath and stills.
"Please!" Harry screams.
A smoky chuckle. "Perhaps next time, Mister Potter."