Author's note: I am deeply sorry for the story below. I was challenged by a friend to write a crossover between the Hitchhiker's Guide to the Galaxy and Harry Potter during a conversation about ill-judged cross-over fic.

I declared it should not be done.

She told me to do it.

So I did.

Mercifully, it's not a cross-over as such, as strange men do not, in fact, appear on a Chesterfield sofa in the middle of the Quidditch pitch, nor do towels play a prominent role, but I did manage to combine the two.

So there, Blue :-D

A Treatise On the Origins of Independent Flight in the Wizarding World

This was not entirely how Hermione had envisaged her job interview. For one thing, she'd expected it to take place in an office, for a start. She certainly hadn't expected to be greeted by a scrawled note stuck to the nose of the gargoyle guarding the stairs to the Headmaster's office.

Two words. Two barely legible words was apparently all the courtesy she warranted. But then, what had she expected? Even civility was probably expecting too much. He may have mellowed in the years since the war, but the Headmaster was still prickly in the extreme. Irritably puffing a spiral curl out of her eyes, she thought back to her schooldays and tried to remember the quickest route to the Astronomy Tower.

Still cursing bloody-minded, inconsiderate arses who made job interviews into pointless games of hide and seek, albeit slightly more breathlessly than before, she emerged onto the top of the tower, only to see a flicker of black robes as the wizard she was seeking stepped out into nothingness. Apparently this interview had been, in actual fact, an invitation to witness the spectacularly messy suicide of the incumbent Headmaster. With a cry, Hermione launched herself across the top of the Astronomy Tower, wand in hand. Perhaps if she was fast enough she might be able to arrest his fall…

Hanging half over the parapet, arm outstretched, she was stunned to find herself face to face with the Headmaster of Hogwarts.

Startled and flustered, she hung there, gaping slightly, staring in shock at the figure hanging in the air before her. Very, very slowly, she lowered her wand and risked a cautious look down. Sure enough, there was a distinct absence of mangled corpse at the base of the tower. That probably meant that the person floating three feet away, in a somewhat unlikely manner, admittedly, was probably not a hallucination. Probably. Bringing her gaze back up, she gave a rather wan smile.

"Er, hello Headmaster Snape." She managed weakly. "Had you noticed that you appear to be flying?"

"Really?" he snapped, "I'm flying?" For a moment he seemed to dip slightly in the air, and she thought she noticed a flicker of alarm cross his face. She dismissed the idea, as his usual impassive mask was back in place before the thought was fully formed. "Well well, Mrs Weasley, your observational skills do surprise me."

"Ms Granger," she sighed, as he drifted to perch on the top of one of the crenellations at the tower's edge. "I retained my maiden name for my professional life, and job interviews are a professional occasion. Or, I should say, they are usually a professional occasion."

"Ah yes, the interview," he said mildly, "to consider your suitability for the History of Magic position."

She gnawed at her lip, the desire to get on with the interview she had been expecting warring with her urge to know just how Headmaster Snape had managed to fly. There was no contest, really.

"It's impossible!" she squeaked, unable to reign it any longer. Frustrated that he seemed to have made this statement of known fact nonsensical, she continued. "I've studied historical evidence, theoretical studies, conducted extensive interviews with the portraits of notable figures attributed with the skill, and all these sources agree that independent flight is. Not. Possible."

"Well, Mrs Weasley, I can apparently achieve the impossible," he replied smugly.

"Ms Granger!" she muttered. "Name kept for professional purposes damn you." His only response to this was to stare at her blankly, so she blurted the first thing that popped into her head.

"Did you learn from him? From… …Voldemort?" No sooner than the words had crossed her lips, she cringed. Oh yeah, well done Granger, remind him of the maniac who tried to do him in using a giant snake, why don't you.

To her amazement, this didn't trigger an explosion of epic proportions. He merely studied her intently, a frown of concentration as he appeared to weigh up his options.

It was the other way round actually," he said at length, "I on the other hand learned from a book, Mrs Weasley, although I'm sure that the idea of learning anything from a book comes as a shock to you."

"Granger!" She ground out, exasperated. Curiosity demanded that she get to the bottom of this, against all her instincts, which screamed that you did not interrogate Snape. Ever. Particularly if you wanted that job. "Which book? Is it somewhere in the library?"

The infuriating man smirked.

"I very much doubt that the book I used will be found within the walls of Hogwarts, or any other magical library."

"Well, as you're clearly not going to tell me where to find the book," Hermione snapped, "I suppose the chances of you simply telling me how you do it are slim!" She considered this for a moment, allowing her annoyance to subside a little. "Which does rather beg the question of why, in the name of Merlin and his little blue pixies, you summoned me up here in the first place?"

"." If she hadn't been so close, she would have missed it entirely. The words had been whispered and run together, as if saying them aloud was something that should not be done.

"You do WHAT?" her voice leapt at least two octaves. If she didn't know that it was impossible, she would have sworn that the Headmaster was blushing furiously. Completely ludicrous, of course. A trick of the dying light.

"Really. Ithrowmyselfattheground. Andmiss." His voice was marginally louder, and infinitesimally slower this time, but it was enough to confirm that her ears had not deceived her.

"You throw yourself at the ground?" she queried, derision creeping into her voice despite her best efforts to quash it. "And miss?" No, she hadn't been mistaken; the man before her really was blushing, high spots of colour staining his cheeks. She cocked her head to one side as she considered this. She had to admit that the concept seemed familiar, and it was painfully obvious that the provenance of this skill wasn't something that the Headmaster was comfortable discussing. This was puzzle she could not resist. So, a book, but not one from the Hogwarts library. Not a Dark text either. Something that was more than a little embarrassing, if it could make Snape blush. In fact, she thought slowly, not a magical book at all! Headmaster Snape was a half-blood, wasn't he? And at this, realisation dawned. Of course his explanation had sounded familiar!

"Are you seriously trying to tell me that you taught yourself to fly from a Muggle novel?" she began, and then followed the thought to its natural conclusion. "More to the point: you instructed Voldemort on the art of flight, as imagined by a Muggle author?" The preposterous nature of the whole exchange finally sank in, and Hermione began to laugh. She rolled away from the parapet and howled with mirth.

When her gasping sobs of laughter had abated, she looked up to see him leaning against the wall, arms folded and the slightest hint of a smile on his face.