The crack startled Harry almost more than the throb of resentment in his belly. He swung again, ready for the hard smack this time, before stumbling backward, palms stinging from the impact. Now was the time to run as if his life depended on it, but he was mesmerised by what a slap actually did. How shockingly the blood rushed to the surface. How it glowed against skin gone frighteningly white.
His hands felt on fire; he'd connected with bone. The marks he'd left blossomed, spreading streaky and crimson, looking hot to the touch.
The black eyes glaring back at him blazed with violence.
Snapping out of it, Harry made a break for the door. A harsh grip nearly wrenched his arm from its socket, and he was thrown against the wall. Then Snape was on him, pinning him against the stone, stark cheekbones, wild eyes, the welts from Harry's hands like an actual burn. Hot breath hissed between his teeth like some variant of Parseltongue Harry had never heard before.
"My turn," Snape murmured, and Harry's heart ricocheted madly in his throat. This close, the slapmarks were all he could see, radiant with hatred. "Don't worry." Snape's voice was sultry and low, vibrating with barely contained rage. "I promise not to touch your famous face."
His hands slithered snake-graceful down Harry's body, fingers fitting like iron bars around his buttocks.
"Drop your trousers," he whispered in Harry's ear, "then bend over."
The or else was as unmistakable as a slap.