Not all the time, though, Harry argued with himself. They didn't fight Quirrell with me. They didn't take on Riddle and the Basilisk. They didn't get rid of all those Dementors the night Sirius escaped. They weren't in that graveyard with me, the night Voldemort returned…

Hermione listened closely. When Harry had finished, she said slowly 'You're worried You-Know-Who's controlling her like he controlled Quirrell?'

'Well,' said Harry, dropping his voice, 'it's a possibility, isn't it?'

'I suppose so,' said Hermione, though she sounded unconvinced. 'But I don't think he can be possessing her the way he possessed Quirrell, I mean, he's properly alive again now, isn't he, he's got his own body, he wouldn't need to share someone else's. He could have her under the Imperius Curse, I suppose…"

'For disrupting my class with pointless interruptions,' said Professor Umbridge smoothly. 'I am here to teach you using a Ministry-approved method that does not include inviting students to give their opinions on matters about which they understand very little. Your previous teachers in this subject may have allowed you more licence, but as none of them - with the possible exception of Professor Quirrell, who did at least appear to have restricted himself to age-appropriate subjects - would have passed a Ministry inspection -'

'Yeah, Quirrell was a great teacher,' said Harry loudly, 'there was just that minor drawback of him having Lord Voldemort sticking out of the back of his head.'

This pronouncement was followed by one of the loudest silences Harry had ever heard. Then -

'I think another week's detentions would do you some good, Mr Potter,' said Umbridge sleekly.

Was this why Dumbledore would no longer meet Harry's eyes? Did he expect to see Voldemort staring out of them, afraid, perhaps, that their vivid green might turn suddenly to scarlet, with catlike slits for pupils? Harry remembered how the snakelike face of Voldemort had once forced itself out of the back of Professor Quirrell's head and ran his hand over the back of his own, wondering what it would feel like if Voldemort burst out of his skull.

He felt dirty, contaminated, as though he were carrying some deadly germ, unworthy to sit on the Underground train back from the hospital with innocent, clean people whose minds and bodies were free of the taint of Voldemort… he had not merely seen the snake, he had been the snake, he knew it now…