Here, he began to pace up and down, past the two beds and Phineas Nigellus’s empty picture frame, his brain teeming and seething with questions and ever more dreadful ideas.
How had he become a snake? Perhaps he was an Animagus… no, he couldn’t be, he would know… perhaps Voldemort was an Animagus… yes, thought Harry, that would fit, he would turn into a snake of course… and when he’s possessing me, then we both transform… that still doesn’t explain how I got to London and back to my bed in the space of about five minutes… but then Voldemort’s about the most powerful wizard in the world, apart from Dumbledore, it’s probably no problem at all to him to transport people like that.
And then, with a terrible stab of panic, he thought, but this is insane—if Voldemort’s possessing me, I’m giving him a dear view into the Headquarters of the Order of the Phoenix right now! He’ll know who’s in the Order and where Sirius is… and I’ve heard loads of stuff I shouldn’t have, everything Sirius told me the first night I was here…
There was only one thing for it: he would have to leave Grimmauld Place straightaway. He would spend Christmas at Hogwarts without the others, which would keep them safe over the holidays at least… but no, that wouldn’t do, there were still plenty of people at Hogwarts to maim and injure. What if it was Seamus, Dean or Neville next time? He stopped his pacing and stood staring at Phineas Nigellus’s empty frame. A leaden sensation was settling in the pit of his stomach. He had no alternative: he was going to have to return to Privet Drive, cut himself off from other wizards entirely.
Well, if he had to do it, he thought, there was no point hanging around. Trying with all his might not to think how the Dursleys were going to react when they found him on their doorstep six months earlier than they had expected, he strode over to his trunk, slammed the lid shut and locked it, then glanced around automatically for Hedwig before remembering that she was still at Hogwarts—well, her cage would be one less thing to carry—he seized one end of his trunk and had dragged it halfway towards the door when a snide voice said, “Running away, are we?”