"Well, we're coming on," Dumbledore said, looking over his half-moon spectacles at his assembled staff. "So far we have a mountain troll – thank you, Professor Quirrell – a prime specimen of Devil's Snare, some excellently charmed keys –"
Flitwick beamed at him.
" – a most ferocious three-headed dog, called, er –"
"Fluffy," supplied Hagrid, grinning fondly.
"Ah, yes... but we still require at least two more defensive measures for the Philosopher's Stone. Just to be sure. Does anyone have any suggestions? Severus?"
"I know a really good curse which would liquefy any intruder's bones and turn them into a puddle of jelly," said Snape, glancing at his headmaster without much hope.
Dumbledore gave him that pitying see, this is why I won't give you the Defence Against the Dark Arts position look. "I think it would be better if you confine yourself to something involving potions, Severus," he said. "Preferably non-lethal potions."
Snape stiffly inclined his head, his expression unreadable.
"... and these were my best students! It wasn't even as if any arcane knowledge of Potions was necessary; simple logic should have told them..."
"Never mind, Severus," Professor McGonagall interrupted soothingly, handing him a cup of tea, "as I was saying to my first year Transfiguration class only the other day, many of the greatest wizards and witches don't have an ounce of logic."
Snape scowled. "Well they should," he said grumpily. "There's nothing about the possession of magic which precludes ordinary common sense. It's disgraceful!"
It did, however, give him an idea.
"Size –" he muttered crossly, "what the hell rhymes with size?"
"Lies?" suggested Argus Filch helpfully. "Cries? Wise?"
"No, no, no..."
Another ball of crumpled parchment joined the growing pile on the staffroom floor.
"Danger lies before you, while safety lies behind,
Two of us will help you, whichever you would find,
One among us seven will let you move ahead,
Another will transport the drinker back instead,
Two among our number hold only nettle wine,
Three of us are killers, waiting hidden in line.
Choose, unless you wish to stay here for evermore,
To help you in your choice, we give you these clues four:
First, however slyly the poison tries to hide
You will always find some on nettle wine's left side;
Second, different are those who stand at either end,
But if you would move onwards, neither is your friend;
Third, as you see clearly, all are different size,
Neither dwarf nor giant holds death in their insides;
Fourth, the second left and the second on the right
Are twins once you taste them, though different at first sight."
Minerva McGonagall looked shocked. "We are merely trying to protect the Stone, Severus, not kill anybody who attempts to steal it. Dumbledore did say non-lethal potions, if you recall."
"Oh, and having a limb torn off by Hagrid's pet dog, or being strangled by a psychotic vegetable is perfectly acceptable?" sneered Snape.
"But, Severus," she protested, "poison? That seems rather drastic. Could you not use a sleeping draught, instead?"
"No," said Snape, his black eyes glittering, "poison. It must be... sufficient... deterrent."
Minerva sighed. It was at times like these she remembered that Severus Snape had been a Death Eater.
Ah, there was an idea. An unpleasant smile twisted Snape's thin lips. Those nosey brats had already shown more interest in Nicolas Flamel than was good for them. If he could think of a way to finesse them into investigating the third floor corridor, even Dumbledore would have to admit that anything which befell them there would be their own fault.
Now humming happily to himself, Snape extinguished the flame under his cauldron and decanted the poison into three of his most enticing-looking bottles.
With any luck, he might soon be rid of the Golden Trio. Forever.