Harry Potter and the Methods of Rationality

But, as Hermione had explained to Millicent, prophesying wasn't controllable, there was no way to ask for a prophecy about anything in particular. Instead (the books had said) there was a sort of pressure that built up in Time, when some huge event was trying to happen, or stop itself from happening. And seers were like weak points that let out the pressure, when the right listener was nearby. So prophecies were only about big, important things, because only that generated enough pressure; and you almost never got more than one seer saying the same thing, because afterward the pressure was gone. And, as Hermione had further explained to Millicent, the seers themselves didn't remember their prophecies, because the message wasn't for them. And the messages would come out in riddles, and only someone who heard the prophecy in the seer's original voice would hear all the meaning that was in the riddle. There was no possible way that Millicent could just give out a prophecy any time she wanted, about school bullies, and then remember it, and if she had it would've come out as 'the skeleton is the key' and not 'Susan Bones has to be there'.

Millicent had been looking rather frightened at this point, so Hermione had relaxed her fists where they'd been jammed on her hips, calmed herself down, and stated carefully that she was glad Millicent had helped them, but they had sometimes walked into traps following what Millicent said, and so Hermione really did want to know where the messages had actually come from.

And Millicent had said in a small voice:

But, but she told me that she was a seer...

Hermione had told Daphne not to press it, after Millicent had refused to give up her source. It wasn't just that Hermione had felt awful about the scared look on Millicent's face. It was that Hermione had a strong feeling that if they did find the person who'd been telling Millicent things, why, they would turn out to just be finding envelopes under their pillow in the morning.

She was getting that same despairing feeling she'd gotten in the battle before Christmas, looking at Zabini's charts with all the colored lines and boxes and... and she had only just now realized what it meant that Zabini had been the one showing her that chart.

Even for a Ravenclaw, she felt, there was such a thing as having your life get overly complicated.

Hermione began ascending a short spiral of yellow marble steps protruding from a central spine, a poorly-kept "secret" staircase that was actually one of the fastest ways up from the Slytherin dungeons to the Ravenclaw tower, but which only witches could traverse. (Why girls in particular needed a quick way to move from Ravenclaw to Slytherin and back was something Hermione found a bit puzzling.) At the top of the staircase, now that she was away from Slytherin places and back into the main parts of Hogwarts, Hermione stopped and took off Harry's invisibility cloak.

After her pouch had swallowed the cloak, Hermione turned right and started to walk down a short passageway, now automatically keeping an eye out in all directions without really thinking about it, and her constantly-scanning eyes glanced into a shadowy alcove -

(fleeting disorientation)

- and then a rush of shock and fear hit her like a Stunning Hex over her whole body, she found that without any thought or any conscious decision her wand had leaped into her hand and was already pointed at...

...a black cloak so wide and billowing that it was impossible to determine whether the figure beneath was male or female, and atop the cloak a broad-brimmed black hat; and a black mist seemed to gather beneath it and obscure the face of whoever or whatever might lie beneath.

"Hello again, Hermione," whispered a sibilant voice from beneath the black hat, from behind the black mist.

Hermione's heart was already pounding hugely inside her chest, her witch's robes felt already sweat-dampened against her skin, there was a taste of fear already in her mouth; she didn't know why she was so suddenly filled up with adrenaline but her hand gripped harder on her wand. "Who are you?" Hermione demanded.

The hat tilted slightly; the whispery voice, when it came forth from the black mist, sounded dry as dust. "The last ally," spoke the sibilant whisper. "The one who finally answers, when no other will answer you. I am perhaps the only true friend you have in all Hogwarts, Hermione. For you have now seen how the others stayed silent when you were in need -"

"What's your name?"

The black cloak rotated slightly, back and forth, it didn't look like shoulders shrugging, but it conveyed a shrug. "That is the riddle, young Ravenclaw. Until you solve it, you may call me whatever you wish."