Disclaimer: See Chapter 1.
Alone in his dorm room, with every other occupant either grieving or celebrating, Harry paced. He knew already that it wouldn't help, as he had been pacing for nearly an hour now, and the inexplicable uneasiness and urgency had only increased. But he paced nevertheless, because he didn't know what to do. Every fibre of his being urged him to go, right now – but he didn't know where to and anyways, after Hermione's very thorough chewing out over following a random unknown Patronus, he had promised himself he wouldn't go into any more potentially risky situations just because it felt right. But he was so bloody exhausted and he wanted to sleep, and the uneasiness and urgency were making his nerves prickle and the hair on the back of his neck stand up and how could he possibly sleep like that? He just wanted to sleep…
Harry's resolve abruptly broke. He disappeared from the dorm room with a nearly inaudible pop, with no destination in mind, just following his instincts. Had he been thinking rationally, of course, he would have known that he couldn't apparate in Hogwarts. But he wasn't – and perhaps this was a good thing, because if he had been thinking rationally, he would never have tried to break such a cardinal law, and he certainly would never have succeeded. It was the last impossible thing the Boy-Who-Lived would ever do in his life.
Barely a moment after disappearing from his dorm room, Harry appeared again. He was clutching a small stone in his hand. Without letting go of the stone, he fell onto his bed and was instantly fast asleep.