Severus stared dispassionately at the derelict shack propped on haphazardly on the hill just beyond the Whomping Willow. Gods, how he loathed that place. The mere sight of it triggered a series of unwelcome memories of his near-death experience as a teenager to the surface, bringing with them an insidious feeling of dread that threatened to paralyse him. A lesser man might have turned and fled in the face of such terror, but Severus was nothing if not brave and he refused to let the situation get the better of him. It's just a dilapidated, wooden, lean-to, nothing more.
Except it isn't, is it? The shack had long been used as a safe place for those afflicted with lycanthropy to wait out their monthly change without being a risk to others. Prior to the discovery of an effective wolfsbane potion, the Whomping Willow had proved a most reliable and resilient guardsman protecting inquisitive students from getting in harm's way. Another ingenious idea of Albus's to allow him to admit werewolves to Hogwarts without the Ministry learning of the danger he was recklessly placing the students in his care in. Granted, very few knew the secret to immobilising the great tree, and therefore only a handful of people had ever been able to access the roughly hewn earth passage at its base which led straight to the shack – but it was a temptation, an irresistible and seemingly impossible challenge that had landed many a student in the infirmary with willow-related injuries.
Severus had only returned to the shack once since that fateful day in his youth when he had been lured there by Sirius Black. Unbeknownst to Severus, Remus Lupin had been ensconced there, waiting out the days until the new moon returned him to his human form. Severus had discovered his secret in the most terrifying and very nearly, deadly way. The second time he had, rather embarrassingly, been rendered unconscious by a triple-combined expelliarmus, courtesy of a trio of third years. The memory still haunted him.
How ironic that fate should bring him back here as a grown wizard, to confront one of his childhood tormentors, who coincidentally, was now a fully grown werewolf. He fingered the cold glass of the potions' bottle and steeled himself. Third time lucky.
Steeling himself, he took a deep breath and immobilised the willow with a wandless spell before moving silently into the tunnel. He did not fear much these days, but the terror of the day in his past haunted him, and he found his hands shaking as he moved towards the small, rough door that marked the entrance to the shack. He pushed it open slowly, wincing as the rusted hinge let out a deafening screech. As the room came into view, he breathed a huge sigh of relief to see the apparently still-human form of Remus Lupin standing with his back to him, gazing at the moon as it began to rise in the darkening sky.
"Lupin, I have the wolfsbane –" he spoke, his voice sounding more confident that he felt. Lupin did not acknowledge his presence. The silence stretched out between them and he felt the hairs on the back of his neck begin to stand up. Something wasn't right. He took an involuntary step back as the professor turned in his direction. His breath caught in his throat and he felt his heart begin to race, thudding uncomfortably as Remus Lupin turned to face him.
Remus stared at Severus without really seeing him. He thought he might recognise the man – he seemed very familiar to him. A faint voice he recognised but could not place screamed in his mind to warn the man in black but with the change almost upon him, the voice rapidly faded away to nothing to be replaced with an all-encompassing hunger. A thin slither of moonlight crept through the dilapidated wooden cladding of the shack and his eyes met those of the familiar man just as the light crept slowly across the floor and fell onto his feet. He saw realisation dawn in those obsidian orbs, quickly replaced by fear as the black-clad man took another slow step backwards.
Remus sniffed the air around him. He detected something that made his mouth slaver, and what little remained of his humanity retreated to a place far inside his mind as the animal in him took over. He felt bones shifting, muscles lengthening and he threw his head back and howled as fur and claws burst through his skin.
Severus let out an involuntary cry as the man known as Remus Lupin distorted and stretched grotesquely before him. For a moment he could do nothing except stare in fascinated horror as the werewolf took form, as bones snapped and reformed and soft hands sprouted fur and razor sharp claws. Move, Severus! His mind screamed at him, and he fumbled behind him for the door without taking his eyes from the shifting form. He edged slowly backwards, hoping the change had distracted the beast long enough for him to slip out unnoticed. His hands were slick with sweat as he grasped the handle and yanked hard, stumbling backwards through the doorway. He felt the cold earth of the tunnel behind him and hesitated as the werewolf turned his head towards him, pale blue eyes locking onto his. It howled.
Fuck. Severus screamed in his mind as he turned and ran for his life. The beast thundered through the door and hurtled after him and he barely had a chance to dodge as a huge paw smashed into the earth over his head sending debris into his face. Spluttering he drew his wand and cast a rapid shield charm just moments before the second paw smashed into it, inches from his face. The wolf snarled in frustration and Severus took the moment to shoot a blast of flame towards it before turning and running towards the narrow slice of moonlight he could see in the distance. The wolf growled as the flames singed its face before bounding again after his prey.
Severus burst out into the crisp air beneath the whomping willow and stopped dead in his tracks. In the growing darkness he could just make out three forms moving swiftly towards him – the unmistakable, tall, pointed hat of McGonagall, a figure of a very small stature – undoubtedly Flitwick but the third, looked like - no – Hermione. What was she doing her for Merlin's sake? She was supposed to be restocking his supply of Wolfsbane in the safety of his private lab! Of course, Minerva! Damned, foolish Gryffindors!
"Severus!" Hermione yelled as she drew nearer, her face pale and frightened in the moonlight, her chest heaving as she came to a stop some distance from him. He stared at her in mute horror and without a moment's hesitation he threw a disillusionment charm at her. She disappeared with a surprised squeak as the spell hit her square in the chest, a faint rippling of the air the only sign something corporeal remained there. She would be mad, if he survived, but so be it. He wasn't taking any chances with her life.
A ravenous, rampaging werewolf would make short work of them all if he didn't find a way to hold it off, to give the others a chance to get back to the safety of Hogwarts where the castle's enchantments would protect them. Should they remain, odds were that at least one of them would end up hurt, killed or afflicted by the curse. He didn't know which was worse – death, or being forced into the terrible existence that was being afflicted by lycanthropy and dictated to by the changing of the moon. He didn't want that for anyone, not even Remus Lupin, no matter his feelings for the man. Even with numbers in their favour, werewolves were legendarily fast and violent, it wasn't a gamble he was willing to take.
"Severus!" Hermione again, closer this time.
"Severus – move!" Minerva screamed breathlessly. She had come to a stop beside the disillusioned Hermione and was trying to catch her breath as she reached for her wand.
Suddenly he felt the hairs on the back of his neck prickle and the whisper of hot breath on the exposed skin above the high collar of his coat. He saw Minerva freeze, terror etched on her ashen face. Her face said all he needed to know.
Chest heaving, heart thudding painfully in his throat, Severus summoned his courage and turned slowly, his wand arm coming up in the direction of his colleagues and without hesitation, diverted the bulk of his magical reserve in casting the strongest shield charm he could. As the shimmering shield rose around them, he looked up to find himself staring straight into the demented eyes of a fully grown werewolf. There was no trace of Remus in that terrifying face. For a brief moment he felt as though it was smiling at him and he felt the insane urge to laugh at the madness and sheer terror of it all. The werewolf regarded him for a moment, sniffing the air around his face. It was just inches from him and he fought the urge to react, standing as still as he possibly could. For a moment, Severus thought he had won the beast over – or that Remus had managed to exert some control but as a heavy clawed paw smashed into the left side of his head he realised that he was utterly wrong. He heard a strangled cry from Minerva as the impact threw him heavily to the ground. He landed on his hands and knees, and he shook his head as his vision swam. Panting he scrambled to his feet, swaying dizzily as he felt the warm rush of blood from a wound near his hairline. The werewolf advanced, smelling blood. Incensed, it threw back its head and howled.
"Severus – the willow!" Minerva shouted, and he realised she was trying to release the willow from its temporary binding but was being prevented by his shield spell. There was some logic in that, he thought briefly before a second clout of a giant paw flung him backwards to collide with the trunk of the tree. The impact drove the breath from his lungs and he heard, rather than felt, bones breaking. He tried to draw a full breath but a crushing pain in his chest turned it into a series of shallow gasps. He was in trouble. Groaning, he slumped onto the ground, back against the ancient tree. His vision was darkening at the edges. He was going to die here. The werewolf advanced slowly, clearly enjoying playing with his prey. It stopped in front of Severus, saliva dripping from its great jaws and opened its mouth wide in a horrifying parody of a laugh. Severus took the only option available to him and lurched forward, thrusting the wolfsbane potion from his pocket into its mouth, bottle and all, and pulled down hard on the wolf's upper jaw. He winced as the bottle smashed between its teeth. It howled in agony as the potion surged down its throat and fragments of glass sliced into its gums. Severus barely had time to register his success before he felt a hot, searing pain in his side as a set of razor-sharp claws cleaved into him, spearing him like a piece of meat. He was hoisted into the air and had the brief sensation of flying before he smashed into the ground a few feet from his shocked colleagues. Without warning, his stomach heaved and he vomited an alarming quantity of dark red blood onto the floor before them. Chest heaving, he used what little strength remained in him to raise his wand as the werewolf advanced on him once more. This was his final chance, he realised, if he failed, he was dead. It was clear to him that his injuries were severe and his chances of surviving this were already against him. His arm shook uncontrollably in protest as he forced it up, his wand directed at the Whomping Willow,
"Incarcerous," he whispered and as the spell burst from his wand, he felt the last of his strength desert him and he collapsed back to the ground, his wand rolling out of his infirm hand and coming to rest amongst the gorse. The willow's long spindly branches reacted instantly, springing forth and wrapping themselves tightly around the werewolf's limbs and pulling taut. The werewolf howled in rage as it was raised from the ground and held immobile by the magical tree. It struggled against the bonds, but even a fully grown werewolf was no match for such a powerful entity, and he subsided, defeated. Then all was silent.