Harry skidded to a halt outside the Defense Against the Dark Arts classroom, pulled the door open, and dashed inside. 

"Sorry I'm late, Professor Lupin. I --"

 But it wasn't Professor Lupin who looked up at him from the teacher's desk; it was Snape. 

"This lesson began ten minutes ago, Potter, so I think we'll make it ten points from Gryffindor. Sit down." 

But Harry didn't move. 

"Where's Professor Lupin?" he said. 

"He says he is feeling too ill to teach today," said Snape with a twisted smile. "I believe I told you to sit down?" 

But Harry stayed where he was. 

"What's wrong with him?"

 Snape's black eyes glittered. 

"Nothing life-threatening," he said, looking as though he wished it were. "Five more points from Gryffindor, and if I have to ask you to sit down again, it will be fifty." 

Harry walked slowly to his seat and sat down. Snape looked around at the class. 

"As I was saying before Potter interrupted, Professor Lupin has not left any record of the topics you have covered so far --" 

"Please, sir, we've done boggarts, Red Caps, kappas, and grindylows," said Hermione quickly, "and we're just about to start --" 

"Be quiet," said Snape coldly. 

"I did not ask for information. I was merely commenting on Professor Lupin's lack of organization."