Size, they say, is not important. What really counts is what you do with it.

This may be true for unimportant things like penises, cars, magic wands and truncheons (spot the word that doesn't belong in the group and explain why) (1), but it certainly isn't a valid statement where stirring rods are concerned.

The importance of the stirring rod's dimensions has got nothing to do with the fact that most potions masters are men, who, according to the Beginner's Guide to Freud, have to compensate for undersized body parts (2). Oh no. The length and girth of a stirring rod determine the impact of its movements on the potion. If you don't believe it, try to brew a simple Pepper-Up with a thicker, longer rod. Or rather, pluck up the courage to sample the finished product. What comes out of not exactly your ears won't exactly be smoke. It doesn't exactly cure your cold either, but you might stop coughing, because coughing and diarrhoea aren't exactly a fortunate combination.

QED – the proportions of a stirring rod are of enormous importance.

Potions masters do have a tendency to take their art and consequently themselves very seriously. They're not fond of jokes made at their expense, and they get very touchy indeed whenever people, especially of the female persuasion, answer the perfectly civil and innocent request 'I need a bigger stirring rod, please' with a snort and a muttered 'I bet you do.'

It is, as Tom Puffett (3) would justly remark, not fair on a man or his rod.

Severus Snape was, in many respects, the archetypal potions master. He despised foolish wand-waving (because, as the Beginner's Guide to Freud would very reasonably point out, have you ever seen a man with two big toes? To which you'd have to reply yes, which goes to show that the Beginner's Guide to Freud isn't a very reliable compendium), he was both proud and jealous of his art, he was reclusive and of a contemplative nature, and he was a patient man. If, that is, people didn't make lewd remarks about stirring rods. But that, too, makes him the embodiment of potions masterdom.

The night of Voldemort's defeat, Snape had survived Nagini's lethal bite only thanks to his own skills. Not being dead, however, didn't mean that he had anything that could by rights be called a life. He had an existence, and had not one Hermione Granger decided that he deserved more than that, who knows what he might have done to himself.

Snape's existence began to look surprisingly like a life the moment Hermione Granger, recently out of Hogwarts (which especially in her case must not be confused with "out of the schoolroom" unless you have a death wish) refused to be deterred by his angry grunts and invectives and declared that she'd decided to become his apprentice. His faint protestations – when the conversation had arrived at that point, vigorous protest was simply beyond his strength – that he didn't take on private pupils were nonchalantly waved away, and the next day Hermione Granger presented herself on his doorstep at the ungodly hour of half past seven a.m., sharpened quills protruding from her pockets. She looked like a very eager and rather endearing porcupine.

A war hero apprenticing with the wizarding world's bogey man didn't go unnoticed for long, which was exactly what Hermione had expected. Whoever asked her about Snape, whether journalist, ministry employee, former schoolmate or shop assistant, got the same answer, i.e. a more or less abridged version of The Life and Times of Severus Snape, Unsung Hero and Badly Wronged Spy.

Slowly, public opinion began to change.

Three months later, Snape had to turn down requests, and those were requests to be put on his waiting list. He was able to offer only five apprenticeships at a time, and even this small number required minute and punctilious time management. Since these were qualities he possessed in abundance, he even enjoyed that aspect of being a private tutor.

There was, however, something he enjoyed infinitely more: teaching Hermione Granger.

She'd always been a most satisfying student, and her obsession with firing off questions and answers at all times had only been a problem in the classroom. During their private lessons he found it most refreshing. Besides, he liked her a lot and thought she was very pretty, but he would have bitten off and swallowed his own tongue rather than tell her.

Hermione, on the other hand, had gradually discovered that ugly doesn't mean unattractive. She'd also realized that non-stop brewing isn't exactly conducive to shiny, fluffy hair, but that his was always clean in the early morning. Moreover, she'd become aware that she genuinely liked the man – she'd missed him dreadfully during the three weeks he'd gone off exploring medicinal plants in South America. What had really upset her while he'd been away were the pictures constantly popping up in her mind of Snape having hot sex with even hotter Latina beauties, and the fits of irrational jealousy they engendered.

Something had to be done.

And once Hermione had decided that something needed to be done, she immediately and stubbornly started plotting until she had determined exactly how, when and where to do it.

It was the How that mad her stare at the bluish patterns of light and shadow on her bedroom ceiling for many sleepless nights.

Hermione's memories of her third year at Hogwarts still made her shudder; that had been the time when lack of sleep had become the thing she feared most. For her, a Boggart would have assumed the shape of a hollow-eyed, pale Hermione with trembling hands and her mental faculties shot to hell.

This was exactly what Snape saw when he answered the door to his favourite pupil, two weeks after he'd returned from his trip to South America.

'Are you ill?' he asked, frowning.

Hermione shook her head. Even her usually springy curls gave an impression of wilted despondency. 'No, just…' She seemed to lose her thread and stared off into the distance, her mouth slightly open.

'Just what?' Snape prompted when thirty seconds had passed without her sentence showing any tendency towards being finished.

'Huh?' Visibly pulling herself together, Hermione focused bleary eyes on Snape. 'Oh, good morning, Professor. How are you?'

'Tolerably well, thank you, Miss Granger. The same, or so it seems, cannot be said about you. What is the matter with you?' He took a step back to let her precede him into the house. 'You look tired,' he added.

'Just… just a little.' The huge yawn that threatened to unhinge her jaw did nothing to add credibility to an already weak lie.

Snape's brows rose. 'Just a little, indeed. You're fibbing, Miss Granger, and, what is worse, you're not even making an effort to do it well. I'd suggest that you go home, lie down and get some sleep.'

'No!' It came out before he had finished his sentence properly. She didn't want to go home, she wanted to spend time with him, even though she still hadn't got any idea when, where or how to make her move. Where wasn't really a problem, since they never met outside his house. How and When were still elusive, though, and… Her mind was abruptly stopped from wandering off on its own, when Snape drew himself up to his full height and shot her a menacing glare.

'You,' he said in his best make-Neville-wet-himself tone, 'are my pupil and therefore my responsibility. You're in no shape to do any brewing today, not with your eyelids at half mast and your hands trembling like... well, like very shaky things. You couldn't even grasp the stirring rod properly! And you know very well the importance of rod control!'

When overtired, Hermione didn't merely lose control of her hands. She just lost control, period. If somebody had told her the old – and let's be honest, not overly funny – joke of 'My dog's got no nose!' – 'How does it smell?' – 'Awful!' she would probably have laughed to the point of suffocation.

And she'd always found rod jokes to be very funny indeed.

'Do you think it would twitch a lot if I held it the wrong way?' she said, barely able to hold back a snigger.

'Don't talk nonsense, Miss Granger, rods don't twitch!'

They'd been slowly but steadily moving towards the half-open laboratory door, and now Hermione was leaning against its frame, partly to keep herself upright and partly to arrange herself in a seductive position. 'Well,' she said, thrusting her chest towards him and reclining her head slightly, 'maybe that was the wrong word. Would it throb, do you think?'

Although her semi-recumbent position didn't look nearly as seductive as Hermione thought – as a matter of fact, she was giving the impression of falling asleep on her feet – the subtext of her question wasn't missed by Snape. 'Behave yourself, Miss Granger,' was his stern reply. 'Such obscenities are beneath you!' While doing his best to keep up his saturnine front, he had to admit to himself that this was by no means an easy achievement, considering the interest his pupil's words were stirring up in his, erm, rod.

'Beneath me, eh?' Hermione's lips parted in a smile that was meant to look provocative. The speck of toothpaste clinging to the corner of her mouth somewhat lessened its effect. 'It wouldn't be beneath me if I knelt down, now would it?' This rhetorical question was followed by an unladylike snort.

'Miss Granger, really, I must insist! Be so kind as to cease this inappropriate behaviour!'

'You haven't seen me behave ina…' Hermione took a deep breath. 'Shit, I'm too tired to speak. In-ap-pro-priately, you haven't seen me behave in… well, that way yet. Believe me, I've been searching for the perfect rod, I really have, and still…' She blinked. 'I haven't found it yet, and certainly not for lack of trying.'

'I am not interested in your sexual escapades, Miss Granger,' Snape retorted coolly.

'No? I rather think you are. Although I wouldn't call them escapades. It was more… more of a quest, really. Quest for the Holy Rod, er, Perfect Grail, no dammit, Perfect Rod. You don't mind that I'm not a virgin anymore, do you professor?'

'Since it is not a requirement you have to fulfil in order to be taken on as an apprentice, no I don't.'

'The perfect rod,' Hermione said dreamily. 'Oh, how I'd love to get my hands on that! Not only my hands of course… You wouldn't let me try yours, would you professor?'

Biting his lip and determined to give her the put-down of her life, Snape stepped through the door into the lab and picked up a slender glass rod. 'Here you are,' he said sardonically and sketched a small bow. Not a wise thing to do in his state of arousal, he realized and winced.

And then, he had to clap a hand over his mouth to prevent himself from yelping, because his favourite pupil, that pretty, well-behaved and eager young lady, was using the rod to caress her nipples through a shirt that suddenly seemed far too thin. 'Miss Granger, what,' he croaked, and then was reduced to silence, because all he could do was focus on breathing regularly while his eyes were following, mesmerized, the progress of the rod's end vanishing between her lips, only to emerge again and be caressed by a soft pink tongue and move down her throat, leaving a faint trail of saliva in its wake. 'Miss Granger,' he repeated weakly and became acutely aware that he didn't know what else to say. 'Stop it!' would have been the correct thing to say, but did he really want her to? 'May I offer you my very own rod?' with emphasis on 'own would have conveyed his intentions, but sounded a bit tacky. 'Oh pleasepleaseplease!' would have been closest to the truth, but quite undignified.

The adrenaline and various other hormones being rapidly pumped through her system momentarily cleared the clouds of exhaustion from Hermione's mind. In a sudden flash of inspiration she realized that sheer tiredness and fatigue had accomplished what she'd been trying so hard to plan for weeks. An evil smile lit her face, and she reflexively licked her lips. Her tongue encountered the toothpaste and rubbed at the stain.

That was the moment when Snape's brain stem decided that dignity ought to be sacrificed to procreation, and the potions master heard himself utter 'Oh pleasepleaseplease!' while he sank to his knees and buried his face in his apprentice's midriff.

Things proceeded very satisfactorily indeed once they'd managed to untangle Severus's hair from the zipper of Hermione's jeans.

The rod was subjected to various tests which it passed with flying colours. Hermione decided to keep it, and it stirred happily ever after.

(1)It's the magic wand, oh gutter-minded reader. Why? Well, because that's the one thing a policeman doesn't have. Tsk.

(2)It is rumoured that men are somewhat particular about the size of their big toes.

(3)Tom Puffett, the indefatigable sweeper of chimbleys, as portrayed in Dorothy Sayers' "Busman's Honeymoon"