Change the Future

HBP 5

Harry felt that the Half-Blood Prince's copy of Advanced Potion Making hardly qualified as a textbook. The more Harry poured over the book, the more he realised how much was in there, not only the handy hints and shortcuts on potions that were earning him such a glowing reputation with Slughorn, but also the imaginative little jinxes and hexes scribbled in the margins and judging by the crossings-out and revisions, that the Prince had invented himself. Harry had already attempted a few of the Prince's self-invented spells. There had been a hex that caused toenails to grow alarmingly fast he had tried this on Crabbe in the corridor, with very entertaining results, a jinx that glued the tongue to the roof of the mouth which he had twice used, to general applause, on an unsuspecting Argus Filch and, perhaps most useful of all, Muffliato, a spell that filled the ears of anyone nearby with an unidentifiable buzzing, so that lengthy conversations could be held in class without being overheard. 

Rory looks at Harry unimpressed having seen the results of one of these spells. 

"Why are you suddenly trying to be my rebel child" James asks looking at Harry who just shrugs. 

The only person who did not find these charms amusing was Hermione, who maintained a rigidly disapproving expression throughout and refused to talk at all if Harry had used the Muffliato spell on anyone in the vicinity. Sitting up in bed, Harry turned the book sideways so as to examine more closely the scribbled instructions for a spell that seemed to have caused the Prince some trouble. There were many crossings-out and alterations, but finally, crammed into a corner of the page, the scribble:

Levicorpus (nvbl)

A few of the older students share a look including the Marauders.

While the wind and sleet pounded relentlessly on the windows, and Neville snored loudly, Harry stared at the letters in brackets. Harry rather doubted he would be able to bring off this particular spell; he was still having difficulty with nonverbal spells, something Snape had been quick to comment on in every D.A.D.A. class. On the other hand, the Prince had proved a much more effective teacher than Snape so far. Pointing his wand at nothing in particular, he gave it an upward flick and said Levicorpus! inside his head.

"Aaaaaaaargh!" There was a flash of light and the room was full of voices: Everyone had woken up as Ron had let out a yell. Harry sent Advanced Potion-Making flying in panic; Ron was dangling upside down in midair as though an invisible hook had hoisted him up by the
ankle.

The hall breaks out in laughter except for Snape and Rory. 

"Sorry!" yelled Harry, as Dean and Seamus roared with laughter, and Neville picked himself up from the floor, having fallen out of bed. "Hang on I'll let you down" He groped for the potion book and riffled through it in a panic, trying to find the right page; at last he located it and deciphered one cramped word underneath the spell: Praying that this was the counter-jinx, Harry thought Liberacorpus! with all his might. There was another flash of light, and Ron fell in a heap onto his mattress. "Sorry," repeated Harry weakly, while Dean and Seamus continued to roar with laughter.

"Tomorrow," Ron said in a muffled voice, "I'd rather you set the alarm clock." By the time they had got dressed, padding themselves out with several of Mrs. Weasley's hand-knitted sweaters and carrying cloaks, scarves, and gloves, Ron's shock had subsided and he had decided that Harry's new spell was highly amusing; so amusing, in fact, that he lost no time in regaling Hermione with the story as they sat down for breakfast. "and then there was another flash of light and I landed on the bed again!" Ron grinned, helping himself to sausages. Hermione had not cracked a smile during this anecdote, and now turned an expression of wintry disapproval upon Harry.