initium
Contrary to the opinions stated in several very popular books, both fiction and nonfiction, werewolves did not leave behind shredded clothing when they transformed. This was fortunate for Remus Lupin because the only thing that could be worse than being stuck in a tree twenty metres above the ground would be being stuck in a tree and naked twenty metres above ground. One prospect was terrifying and the other had the added bonus of humiliation once the body was found.
And his body would be found of that Remus had little doubt, for, you see, wherever his wand was it wasn't with him, and twenty metres is a rather long way down when you lack the means to safely go in that direction.
Of all the ways that he imagined his end coming about, it wasn't like this. If he hadn't been so busy clinging to the branch he was on, he might've been annoyed. As things stood, or rather clung, he was mostly frightened out of his wits. A strange sort of calm set in as the morning sun steadily rose in the east, one that he was fairly certain was shock. Not long after that, something else set in:
Self-preservation.
He was not going to die by falling out of a bloody tree. He would find a way out of this. He would climb down. That last thought, alas, resulted in him looking down which was a very bad thing indeed. His grip nearly gave way on the branch. He scooted back as far as he could, the bark of the trunk digging hard and sharp through his robes. For quite a long time, he swore at himself. Then he screamed for help, the volume of which scattered birds — and rather large spiders — from the trees.
Spiders like that were Acromantulas and Acromantulas meant the Forbidden Forest. How had he ended up here? Scotland wasn't near his cottage in Cornwall. The only way possible would've been through Apparition and werewolves could not Apparate.
Of course, they couldn't climb trees either.
That made him scream again.
Lupin did not know what great timing he had until a voice from nowhere, a voice he somehow knew, seemed to crawl right into his ear to say, 'Although you are a fool for getting yourself into this situation, whoever you are, I suppose I shall help you.'
He looked down, carefully this time, to see a faraway figure in black staring up at him. Three and a half minutes later, he was as disappointed to see Severus Snape as Severus Snape was to see him, which is to say astoundingly disappointed. Being rescued by a childhood nemesis wasn't the ideal start to a day, especially when that nemesis had been a Death Eater a scant six years before.
'You,' Snape said just as Lupin said, 'You?'
Snape's lip curled, which wasn't all that unexpected. He'd worn that look so often in school that it probably came as easy as breathing. The basket in his arms that contained a lot of freshly harvested Potions ingredients was quite the sight, however; it looked as if he was ready to go on the strangest picnic in the land. That was right, he had become a professor after Hogwarts and if he was working under the watchful eye of Dumbledore, he most likely wasn't going to murder a man that he had just helped. But why was he frowning?
He said, 'You're welcome, by the way, Lupin.'
'Er, what?'
The dour man looked disgusted by this bit of confusion. 'For me saving your life, such as it is.'
'Oh, yes, well, thanks,' Lupin said. 'That was rather nice of you.'
(The shock had yet to completely dissipate, obviously.)
Snape snorted, and then said, 'My "niceness" wouldn't have been necessary if you had bothered to use your wand like the wizard you purport to be.'
Lupin frowned. 'Thanks for the suggestion,' he said with irritation, 'but a lost wand is a little difficult to use.'
'One could hardly call it lost.' Snape gave a pointed glance to Lupin's right ear before he whirled away into the shadows of the forest.
For many minutes afterward, Lupin stood there in silent defiance of the tiny weight pressing his ear. Werewolves could not Apparate, they could not climb trees, and they certainly did not misplace their wands.
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Note: Came about from this prompt at the /r/HarryPrompter subreddit
r/HarryPrompter/comments/4j1so7/wp_remus_gets_stuck/