"Your father didn't set much store by rules either," Snape went on, pressing his advantage, his thin face full of malice. "Rules were for lesser mortals, not Quidditch Cup-winners. His head was so swollen --" 

"SHUT UP!" 

Harry was suddenly on his feet. Rage such as he had not felt since his last night in Privet Drive was coursing through him. He didn't care that Snape's face had gone rigid, the black eyes flashing dangerously. 

"What did you say to me, Potter?" 

"I told you to shut up about my dad!" Harry yelled. I know the truth, all right? He saved your life! Dumbledore told me! You wouldn't even be here if it wasn't for my dad!" 

Snape's sallow skin had gone the color of sour milk. 

"And did the headmaster tell you the circumstances in which your father saved my life?" he whispered. "Or did he consider the details too unpleasant for precious Potter's delicate ears?"

 Harry bit his lip. He didn't know what had happened and didn't want to admit it -- but Snape seemed to have guessed the truth. 

"I would hate for you to run away with a false idea of your father, Potter," he said, a terrible grin twisting his face. "Have you been imagining some act of glorious heroism? Then let me correct you -- your saintly father and his friends played a highly amusing joke on me that would have resulted in my death if your father hadn't got cold feet at the last moment. There was nothing brave about what he did. He was saving his own skin as much as mine. Had their joke succeeded, he would have been expelled from Hogwarts." 

Snape's uneven, yellowish teeth were bared.

 "Turn out your pockets, Potter!" he spat suddenly. 

Harry didn't move. There was a pounding in his ears.