Disclaimer: I don't own any rights to Harry Potter.

It starts like any normal first-year Potions class. Ravenclaw and Hufflepuff; not quite such a bad combination as the Gryffindor-Slytherin group that is shortly going to turn his hair white.

They're in their third week of the new school year, and not – quite – as terrible as they could be. There are even one or two who might turn into passable potioneers, with application and hard work. That Spurgeon girl, for example, and the little Muggleborn Maxwell, who had volunteered the information that he liked to help with the cooking at home. Severus had not cut him down to size for that remark, mostly because the gently fizzing Chilblain Concoction in the boy's cauldron was the precise shade of violet that it should be.

Yes; not quite such an atrocious group of dimwits as he usually has to teach, and as he watches their diligently bent heads Severus feels an odd surge of something like satisfaction. He wonders if this is what other teachers feel regularly, and if perhaps this is why people chose to join the teaching profession. He certainly had not chosen.

He flicks his gaze at the board, admiring his own command of the Scribocreta Spell. Beloved of teachers, it saves much of the work of scratching messily with chalk on the blackboard, and Severus is particularly proficient. The handwriting on the blackboard is just like his own, sharp and spiky yet precise. A Potions Master needs precise handwriting, as a single 1 looking like a 2 in a list of ingredients might be the cause of an explosion.

He glances back at the class - and something's wrong.

Wrong.

Severus can feel it. Something wrong about what he's seeing, something small. He can't place a finger on it.

He scans the little faces, looking for a hint of laughter, or a devious glint in a student's eye. But every head is bowed, all eyes downcast to parchment and quills. Not a whisper or a giggle. Severus looks back at the blackboard. He is a Slytherin.

After a few moments, he slides his eyes very, very slowly back towards the class, hoping to catch who-ever – or whatever – it is, unawares. Whatever devious thing it is that they are doing. But – there is nothing to see. Nothing at all, just the quiet students and that irritating sense of wrongness.

Severus knows better than to huff in frustration, much as he would like to do so. It is clearly not misbehaviour of the usual sort. Not that that sort of misbehaviour occurred frequently in his class; he made sure of that. But if it did occur, there would certainly be laughter, that foolish, vapid, pack-laughter that he so despised.

And the students weren't laughing. They certainly didn't look like they had even noticed anything unusual, just quietly copying from the board, looking up every so often, and back down again.

A dark suspicion begins to form in his mind, a suspicion that this is all part of a larger plot. Their good behaviour, their studiousness – it is quite likely that it is all merely a ploy, perhaps orchestrated by an older miscreant, and with some deviously devastating consequence to himself or his classroom. Severus is surprised at the little stab of betrayal that he feels in his chest, but he ignores it.

He looks back at the class, a firm swivel of his head this time, intending to stand up and call them out on the trick – or whatever it is. And perhaps it is because he is not looking for it, but he notices – right there in the middle of the front row – and it almost makes his jaw drop in surprise.

The little Hufflepuff girl's hair is slowly turning pink.

Pink!

She's scribbling industriously on her widely-angled parchment, a small tongue poking out the corner of her mouth, a furrow of concentration puckering her brow. And her light brown hair is gradually changing colour, a streak at a time, to a bright, vibrant pink. There is a big hunk over her left ear and temple that is entirely coloured.

Severus has seen his fair share of accidental magic before, but nothing like this. The little girl – Nymphadora Tonks, he thinks she's called – doesn't seem to be particularly emotional, or excited, and strong emotions are always the trigger for accidental magic in young children. But she is just sitting there, concentrating hard on the copying he has assigned.

He stands up, and walks to her desk. The desks in his classroom are well spread-out, and he places his fingertips on the wood surface to gain her attention and speaks in a quiet voice that won't be overheard by the other students.

'Miss Tonks.'

Her head jumps up and she looks at him with wide eyes, rather frightened, no doubt expecting a reprimand. Severus has a reputation. 'Uh, yes, sir,' she gulps.

'Your hair, Miss Tonks. Were you aware that it is rapidly changing colour?'

A look of horror comes across her little round face as soon as she hears the word 'hair', and her hands fly up to cover it. 'I'm sorry, sorry!' she gabbles, and gives her head a little shake; the hair instantly returns to its usual brown.

Her high-pitched voice has attracted the attention of some of her classmates, and Severus reels in his own utter surprise at what he has just witnessed.

'There is no issue. Back to your work,' he says smoothly, loud enough for their ears, and their heads snap back down.

He looks back down at the little Tonks girl, who is watching him with big worried eyes, grey as rainwater, and speaks quietly again. 'Please see me after class, Miss Tonks.'

A natural Metamorphmagus. It must be! He can think of no other explanation; generally cosmetic spells are fairly advanced, and what he had seen her do had been quite spontaneous. Fascinating.

The end of class comes, and soon it is just Severus, and the little Hufflepuff, standing beside her desk and twisting her fingers. As soon as the door has shut, she starts apologising again. 'Professor Snape sir, I'm sorry, I really am, I didn't mean to, I was just concentrating hard and wondering about the asphodel bit on the board and sometimes it just happens and I'm sorry!' she says in a rush. Her lip is trembling slightly, a fact he chooses not to acknowledge.

'You are not in trouble, Miss Tonks,' he clarifies. 'I was merely interested. Are you a Metamorphmagus?'

She heaves a big sigh of relief, and almost smiles, but not quite. Severus's demeanour is not such that encourages children to smile. Her eyes have changed colour, quite unconsciously. How fascinating. Instead of the grey they had been when she had first spoken, they were sparkling a bright turquoise.

'Yes sir, Metamorf – that's what Mum calls it too, I was born with it and it's really hard to not change since I've been at school, I was practicing before I came but it isn't the same and Gwendy Brigg keeps teasing me about it.' Her face falls a little, then brightens again. 'But I think she's just jealous!'

'Undoubtedly,' he says dryly, in response to her last observation. 'You morph without knowing that you are doing so, sometimes?'

'Oh, yes, quite often, when I forget everything – like when I flew properly the first time, because it was so fun, and when we do really interesting things in class.' She looks up at him innocently, and this time he feels a stab of something like pleasure. Not, of course, that it really matters to him whether first-years find his Potions class interesting.

'Your gift is fascinating,' he says abruptly. 'There is a technique you may find useful in controlling accidental morphing. It is quite simple, and I am able to explain it to you if you wish.'

She nods vigorously, a real, surprised grin breaking across her face this time. 'Yes, please, Professor.'

'Very well. This technique is to be used before you study or engage in any activity that actively stimulates you in any way; for example, your classes and flying lessons. Those activities that you find particularly engaging, as it were.'

She nods seriously, eyes fixed on him. 'May I take notes, sir?'

He nods, and waits as she sits back at the desk, grabbing her parchment and quill, and furiously scrawls a dot point that looks to read something like 'Before doing fun stuff'. Then she looks back up at him, waiting.

'It would be best if you found a place that was reasonably quiet; however, if that is not possible you will have to make do. You must sit down and close your eyes, and make your mind completely clear. Let all your thoughts and feelings drain away.'

She scribbles it all down in a childish hand, pressing so hard he wonders that she doesn't break her quill. 'Make my brain blank,' she murmurs as she writes, and he is rather pleased to see she has couched it in her own terms. A sure sign that a student has understood a concept.

'The last thing you will need to do is focus on how you are breathing. Ensure that you are taking long, deep breaths, although not so deep as to be distracting. Count the breaths: seventy breaths, with each inhale and exhale worth one count. Do you understand?'

Her forehead is furrowed, her eyes thinking. 'So, breathing in is number one, breathing out is number two, then in again is three, out again is…'

'That is correct,' he confirms snappishly before she can go over the whole seventy. 'When you have finished your seventy breaths, your mind should be clear and uncluttered, and your abilities less likely to get out of control.' It is the most basic of beginner's Occlumency exercises, and should, if used correctly, help her to control her accidental morphing.

She beams up at him. 'Thank you sir! I'll practice, I truly will.' She rolls the parchment up carefully.

'You may return to your common room now,' he says, and the child almost skips to the door, as though she is under some sort of Buoyancy Charm. At the door she pauses and looks back, smiling sunnily, and waves a little with her fingers. Severus is tempted to pretend not to notice, but in the end he inclines his neck in a stiff nod of dismissal.

The next day, Severus finds a little box left on his desk. After studying it suspiciously for a few minutes, and performing several diagnostic spells over it, he concludes that it is probably safe and opens it.

Inside is a single, large cupcake, covered in hideously bright pink, fluffy icing and topped with an exuberant cherry. The little folded note next to it reads simply, in a round childish scrawl, 'Thank you Professor'.

(He does eat the cupcake.)

Please leave a review and let me know what you thought!

A virtual pink-iced cupcake (with a cherry) to anyone who gets what the blackboard writing spell means. I have a freshly-baked batch of them to hand out; Severus only got one. ;)