Willow heard the two Slytherins behind her. Kibble and Notro were most definitely the worst of her year and cleanly thrashing them on the mock exams probably hadn't done her any favours.
"Oy monkey features can't run forever" one of them shouted. She could never tell the difference between the two and sometimes she thought that it honestly didn't matter.
I need a place to hide she desperately thought as she turned another corner. Into a dead end. Panicking her hands searched across the cold stone walls of the corridor searching for a secret door to help her. Turning back to the other side she saw a small distressed wooden door that she thought lead to a cupboard of some sort. Pulling it open she dived inside closing the door behind her.
She pressed her ear against the wood as she heard the two approach her hiding spot.
"She must have gone straight" Kibble said and she heard the two run off. Willow lent her back against the door and slid down to the floor.
The room in front of her was dark, moonlight showed small patches of dusty stone floor, and high shelves of burnt items. Fumbling at the sleeve of her robes, Willow pulled out her wand and muttered the lumos charm.
Another brighter stream of light illuminated directly in front of her, revealing several shelves of books and jars of herbs. She reached out and pulled the first book down. It was a new and slightly stained cope of advanced potions making. She placed it back on the shelf and continued into the room. Farther in she high shelves seemed to have been pushed back to create a small den. A dirty old mattress sat in a corner with another pile of books next to it. A low table was filled with yet more books, though these were in two piles, one was burnt and the other was little more than sheets of paper covered in spindly handwriting.
Willow gingerly lifted the topmost burnt book. She could barely make out the title of 'Most potente potiones'. She noticed another larger gap in the shelves surrounding the den and went through. This looked to be a potions lab. Obviously some other students were self studying, not that she blamed them Professor Knightly was awful. Her curiosity piqued she peered into the gently simmering mixture. Willow didn't recognise the potion at all and stepped back. She heard the distant chimes of the school bell signalling curfew and swore, she couldn't head back now otherwise one of the teachers would deduct house points and they were already woefully behind. The last quidditch match against Ravenclaw had found them hundred points behind the next house.
She moved back through to the den and sat on the mattress. It needed bedding so she transfigured some burnt robes into sheets and duvet. She hoped that the other students wouldn't notice her unwashed hair the next day. Extinguishing her wand she drifted into an uneasy sleep.
Severus watched as the girl fell through the door. Her reddish brown hair was loose and fell in waves around her face. The lights in the room of requirement had been dimmed so he could not tell what house she was from. Obviously the room had decided that her need was greater than his at the time otherwise she wouldn't have gotten in.
Typical just as his potion was getting into the fiddliest stages he has to play host, to some dunderheaded student no less. He studied her as she moved further in the light from her own wand illuminating her features. Sculpted angular features and cool grey eyes, he decided she had to be in fifth or sixth year. He smiled as he saw the green stripes on the uniform a Slytherin at least, though a woefully curious one as she nosed around his home. As the bells rang he saw her frown and head towards the bed. She transfigured sheets and seemed to fall asleep quickly.
At least he could risk seeing to the potion now. He crept past her to his lab. Bending over the lilac potion he gently added several crushed leaves. He pulled his wand from his back pocket and stirred the potion six times counter clockwise, three times clockwise then once both ways before repeating. The stirs had to be constantly the same speed until the potion has thickened to a solid mass in the center of the cauldron. He stirred until small patches of sunlight were streaming in through the high windows of the room. He heard movement behind him as the girl woke.
He could either conceal himself again ruining the potion, having to risk stealing from the potions stores again. Or he could let her discover him, after nearly fifteen years of hiding.
He turned his attention back to the potion ignoring the sounds of footsteps behind him and the startled gasp.
Willow woke to the sun streaming down onto her face, someone must have pulled the curtains back. Turning she expected to see the closed drapes of the other girls in her dorm but instead saw the blackened shelves of the room she had found the previous night. Swinging her feet out of bed she searched for her wand, bag and shoes. In that order, the wand she found on top of the books by the bed, the bag was by the door and her shoes were neatly by the table. As she pulled them on she decided to check the potion again, to see if she could recognise it after a night of simmering.
As she went into the lab she saw what was definitely not a student. A tall thin sickly looking man was bent over the cauldron. His greasy long black hair, fell forward obscuring his face and also lay in greasy tangles down his back. She gasped as he straightened up to change hands for stirring, his eyes were black and he had a prominent hooked nose. She was looking at Professor Snape.
"Professor?" she asked as he continued stirring the potion. He made no sign that he had heard her. "I'll be going now then" as she slowly back towards the door she had come through yesterday night.
He moved faster then she thought possibly and she found herself pinned by the throat against bookcases that wobbled against her weight.
"I think not" his voice cracked from under use and she saw how sickly thin he was, how pale his skin had become. "You would talk and I can't have that, I've grown accustomed to my privacy and having hangers on would, " he paused rolling his tongue round his mouth, "detract from my research".
"Yes sir", Willow managed a strangled gasp and she felt the hand loosen and saw him step back. Black eyes studying her face, for a reaction. He saw her hand go towards her wand and moved instinctively.
"expelliarmus" and her wand soared in a graceful arc to his hand. Severus felt a rush of warmth flow through his arm. "I will keep this". He moved towards her this time taking her hand. "You will promise to keep my secret, to aid me where you can?" She tried to back away, squirming at his grip. "Promise!" he demanded.
"I… I promise" she croaked out and a small strand of flame came from her wand and wrapped around their two hands.
"You know what will happen if you break that now?" he asked turning her around and leading her to the bed, pushing down to sit on it. She nodded glumly. He sat in front of her so that their eyes were level. "Take my wand; it's badly broken so you can use that as an excuse to get a new one, then I want a copy of the latest prophet."
Willow nodded and felt calloused hand pulling her up and guiding her to the exit. She was pushed outside and felt a warm whoosh of air as the door closed and disguised itself again as a solid wall. She turned and walked towards the great hall, where the appetising smells of breakfast met her.