AN: My first fic! I am fascinated by the whole teacher-student dynamic, and Snape is so deliciously evil. I have a reasonable idea of where I am taking this. Poor Calliope is going to suffer a bit under the unwanted attentions of the Potions Master. He won't be crossing that line though; don't expect lemons.

Thanks for reading, and please review. I welcome constructive criticism on my writing.

Disclaimer: I don't own anything you recognise. Just havin' a bit 'o craic with JK Rowling's universe.

Double potions, Monday afternoon. Calliope Lode was concentrating, completely focused on the complicated healing potion that was simmering in the cauldron in front of her. It had a distinct purple shade, which was about right, according to the instructions in 'Advanced Potion-Making'. But the textbook also mentioned it should be smelling of almonds and 'casting off a vapour, distinctly lace-like in texture'. Lace-like? How does a vapour even have a texture? She frowned. Her potion was not casting off any vapour, lace-like or otherwise, nor did it smell like almonds. Nothing for it but just to keep going, I suppose. She checked the instructions. She thought the next step was to add a single drop essence of Nightshade; the text warned grimly that too much would not only destroyed the healing properties of the brew, but turn it into a poison. In addition, the potion had to be stirred vigorously while adding the Nightshade. This is going to be difficult. Calliope tried to relax herself with a few deep breaths as she gently held the dripper from the small bottle of essence in her right hand and the ladle in her left. The sixth year Ravenclaw had a good head for potion making theory. She grasped even the most difficult concepts with relative ease, but when actually brewing she lacked confidence, causing her to be nervous. Which in turn made for unsteady hands. Not good in potion making, especially when you need to carry out a delicate action at the same time as a vigorous one.

Willing her hand to not shake, she moved the dripper over her cauldron. She started stirring, her attention so completely dedicated to what she was doing that she was no longer aware of anything outside the ladle, the dripper and the cauldron with potion. Carefully, she released a single drop of the essence of Nightshade and was about to slowly withdraw the dripper as a voiced hissed in her ear.

'Do you need glasses, Miss Lode? Can you not read the instructions, can you not see that the vapour is not lace-like at all? And I don't smell…' Professor Snape never finished his critique, as his sudden appearance had broken Calliope's intense concentration and startled her. She gave out a small shriek, and her right hand jerked upward, the motion releasing several more drops of essence of Nightshade into the potion. The liquid immediately turned a venomous green and started giving off a smoke which caused all those in the immediate vicinity, including herself and Snape, to cough violently as the fumes burned their lungs. Calliope started scrambling for her wand which she knew was on her desk somewhere, but Snape already had his out and with a silent incantation he emptied her cauldron. As the air cleared, the Ravenclaw found the professor's black eyes focused on her, a little smirk playing on his lips. He inserted his wand back into his robes with a dramatic gesture, and gave an exaggerated sigh. All the other students bend low over their own brewing, pretending not to notice the drama unfolding and thanking the gods that it wasn't them.

'Why, is it, Miss Lode, that you are so incompetent when it comes to brewing potions? You demonstrate at every opportunity that you do understand the theory.'

The comment was unfair. While Calliope had certainly always struggled with brewing, and while she had had a bad run recently, over the previous five years she had generally managed to finish her assignments with success. But then of course, Snape was never fair. Sarcastic and cruel, yes, but not fair.

'I do try very hard, sir, ' she said softly. Calliope tried to meet her teacher's gaze. She knew she was blushing. He had that effect on her anyway, but she was also mortified at having caused such a mess. Again. The third time in a school year that had only started a month ago. Not a great start of her NEWT career in potions at all.

Snape snorted. 'Indeed, you try. As for trying very hard? I think not. I have never seen such a discrepancy between theoretical understanding and brewing abilities. You are able to do better. So tell me Miss Lode, when will you start applying yourself to potion brewing properly?'

'I don't know, I mean, I don't understand…' Calliope was becoming more and more distraught, unable to cope with the Potion Master's cruel sarcasm. Her eyes were burning, tears threatening. Then, as she began to comprehend what Snape had just said, she felt a tinge of anger as well. What? I work harder in his classes than I do in any other.

When she failed to respond to his question any further, the potions master sneered, displaying his yellow teeth. 'Most of my first years are capable of adequately handling a dripper. You are a NEWT student. So surely it cannot be incompetence that made you add four times the dose of Nightshade required?'

The anger inside Calliope grew as she considered the insult of his comment. The nerves and tension that her recent problems in potions had caused fed her anger, making her do something no one, not even herself, would have thought her capable of. In a moment of insanity, quiet, obedient Calliope Lode snapped.

'That was your fault!' She blurted it out, then was immediately horrified, instinctively taking several steps back as she saw rage flash on Snape's face before he got himself under control. The entire class drew a collective audible breath, proof that despite appearing to be focused on their work, they were all paying close attention to the encounter between their classmate and the teacher. Undoubtedly, it would be the talk of the school later.

Snape glared at Calliope. His pale face was an expressionless mask, although anger burned in his eyes. 'A most interesting assessment, Miss Lode. Perhaps you would like to elaborate on it after class?' He took a step forward, closing the distance she had created between them and leaned forward until his face, framed by greasy black hair, was level with hers. He spoke softly, voice dripping with sarcasm. 'Since you have evidently finished brewing for the day, I suggest you spend the rest of the class writing up an essay detailing why your potion failed. Which I assure you it had, well before I apparently made you spoil it even further.' Calliope only nodded in response, afraid that she would start crying if she were to try and speak. Snape held her gaze for another moment. Calliope stood frozen to the spot, barely daring to draw breath. Then he straightened and turned sharply in a flurry of black robes. Walking to the front of the classroom, he did not look at back as he spoke again. 'And fifty points from Ravenclaw.'