"This cannot possibly be a good idea," said Severus flatly.

Minerva nodded firmly. "I must say I agree, Albus." For once the Gryffindor and Slytherin Heads were in complete accord. It felt a little strange to Minerva, really. It wasn't that she didn't get along with Severus, of course, but his students were a constant thorn in her side. Albus had (probably accurately) observed that even Salazar himself would not have been able to fix the Dark shadow hovering around the Slytherins of the last few generations, not without summarily executing half of them, but it was still a source of conflict, and she couldn't remember the last time she and Severus had been entirely in agreement about something.

In any case. Bad ideas, see also: The Philosopher's Stone, and Albus' mad plan to bring it from Gringotts to Hogwarts via Rubeus Hagrid.

"Hagrid is perfectly trustworthy," insisted Albus cheerfully, "and Hogwarts is the safest place in the world, they say. Everything will be fine!"

Severus stared at him in clear astonishment. Minerva felt much the same way. "Actually," the potions master objected, speaking slowly, as if to a child, "I was talking about the part of the plan where we tell everyone on staff."

"Ah, but Severus, it is a trap!"

Silence.

Both professors stared at him blankly.

Albus twinkled merrily, waiting for someone to ask. Minerva wasn't sure she was up to it, really.

"What?" asked Severus finally, cautiously.

Apparently, Albus had decided that everything would be twice as fun if he pretended to be crazy. Or, Minerva supposed, he might actually be going crazy. (She wasn't quite sure which was worse.) The headmaster said, as if this were an explanation, "Surely you have heard the proverb that says, 'the best way to keep a secret among three people' - "

" - is to kill two of them, yes," agreed Severus, ignoring Minerva's slightly scandalized gasp. Surely he wasn't implying that he was going to kill Hagrid? "What is your point?"

"Why, of course," smiled Albus, "by contrast, the easiest way to be sure a secret gets out is to tell as many people about it as possible!"

Minerva caught up. More or less. "You mean you want people to know that you are hiding the Philosopher's Stone inside Hogwarts?" Why? She wanted to ask. What purpose could that possibly serve? Albus wasn't usually the sort for pointless braggadocio, at least in her experience.

"Of course not," replied Albus, still unreasonably cheerful, "that would be silly. Everyone would want it."

There was another awkward silence.

"Ah, I see," said Severus, and Minerva's gaze snapped to him, utterly astonished.

"You see? What do you see? This makes no sense!" she protested.

"That is because you are not a Slytherin, Minerva," Severus said in a tone that, for him, might even have been an attempt at being gentle. "The Philosopher's Stone will not actually be hidden behind the elaborate traps we will set up. It will be a monitoring device of some kind, designed to tell us who steals it." He glanced at the headmaster for confirmation.

"Precisely!" said Albus, beaming.

Minerva was boggled. No, indeed, she was not a Slytherin. She had been offered Ravenclaw as a child, yes, but she was a Gryffindor. She could handle military strategy - and she'd found she was quite good at chess, when she tried after the war was over - but plotting of this type was foreign to her. That was for Severus and Alastor Moody and Augusta Longbottom, for the clever Slytherins to whom complex dramas were bread and butter and wine. Still, it unnerved her to be quite so lost. Augusta, at least, usually explained her plots (though Minerva was still not completely sure she understood the series of bribes and blackmail that had been involved in the, ahem, suicide of Lucretia Black-Prewett). This one didn't seem to have gotten any less confusing with explanation. "What? Why?"

Severus, thankfully, took pity on her confusion and kept explaining. "If there is one thing that we can count on Death Eaters to want desperately, it is the Philosopher's Stone," he said. "After all, they're all fundamentally self-absorbed, and if ever there was an easier ticket to a selfishly comfortable life than endless gold and immortality, I cannot name it." Minerva noted with interest and approval that Severus was now referring to the Death Eaters as they, rather than we. He continued, "We can safely expect that any who find out will attempt to steal it." Reasonable enough. She nodded. "Therefore, a theft gives us useful information about who is and is not trustworthy. For example, if Lucius Malfoy were the thief, one might safely assume that I was the one who had told him."

Minerva blinked, and assimilated all that, and nodded again. "I - alright, I suppose that makes sense, although I still don't see why it's quite necessary. Am I to assume that Nicholas Flamel is still in possession of the Stone itself?"

"You may assume that," smiled Albus, and the way he was twinkling at her told Minerva that even if she assumed that, it wouldn't be true.

She sighed. It was probably best just to go back to planning her lessons, and leave all this Slytherining to people who understood it.