It was tempting, briefly, to dress like a sexy librarian.

Common sense prevailed, however; if you're going to be teaching Ruri the way the world works, you should probably lead by example. The people you have to watch out for aren't the ones who look like they're trying, be it to stand out or anything else. Well, except the Leviathan, but when you're capable of disintegrating an island without trying you get a little leeway.

Point is, you're wearing a short, comfortable dress you resized from Kalawarner's collection instead as you lounge in a chair at one of Kyoto's many libraries. It's been a few days since you last saw Nabi, and a visit to Ruri's restaurant let you organise times to meet her: twice every week, on her days off. The idea of a kitsune being beholden to a mortal job is the amusing sort of pathetic, but you suppose it might be the best she can get her hands on for now. You should teach her to steal. Start her off with petty thievery to warm her up to the real kind. They say crime doesn't pay, but that's because the ones that do aren't committed by people stupid enough to admit it.

(The idea of selling her on selling herself is one you shoot down fairly quickly. You don't think Nabi would appreciate the joke, no matter how much she professed to respect Ruri's independence).

You pass the time before Ruri's due to arrive by scratching a privacy ward to the bottom of the desk. It's a simple thing—much like the desk itself, plain brown wood and just enough space for two—designed to make your voices uninteresting and you unapproachable. If you're going to lecture on the supernatural, you'd rather not do it in a whisper. Or have some mousey mortal try to tell you off for being too loud, either.

Unfortunately, it'd take a little more work than you're interested in to make the type of ward that'd let you be the other sort of loud without getting kicked out or arrested – and as fun as that can be, Ruri probably isn't ready for it yet. Seduction—of the mind, not the body—is best done so slowly the victim never has a thought they can't claim as their own, and she's much too lovely to lose to impatient hedonism.

To power up the ward, you press a quick burst of Light into its activation matrix. Literally so, in fact; you've spent most of the past few days and nights as much on reading mathematics textbooks as you have on redesigning old rituals. It makes the most sense to start with the simple ones, and you already knew privacy wards relied as much on probability as they did mind-control. You still don't exactly get Markov chains, but you can pretend well enough for something this basic – even if it fails, you've spent so little strength on it that at worst the desk might become hot to the touch.

Out of the corner of your eye, you spot Ruri's entrance by the way heads turn and one teenager's jaw slacks. She's wearing a kimono—for a given value of kimono, and a given value of wearing—and has even included an obi. How kind of her to return the favour.

She crosses the room toward you, and you shove out her chair with your foot.

"Hey, Sabetha!" she says, not so much slipping as slinking into her seat. The motion exposes a couple of things about how much clothing she's wearing beneath that kimono, and you sigh internally. Really? Looks like you know what your first lesson is going to be about. There's a difference between lascivious and desperate, and you don't particularly enjoy the latter – not when it comes to sex, anyway. You'll draw out a death just to watch a man weep, but in the bedroom the only sort of begging you want to hear is for more.

"Hey, Ruri," you say. "Want to guess what you'll be learning today?"

"Uh…" The quizzical crinkle of her nose is—just possibly—something that maybe other people might perhaps think of as adorable. Not you, of course. "The history of the Grigori?"

The slyness of her smile suggests she's thinking some sort of joke at your expense.

"No," you reply, voice perfectly level. "I'm going to teach you an ancient and fundamental secret of society, one so deep and mysterious your life will never be the same afterward."

Her eyes widen eagerly.

"Tell me, dear Ruri… have you heard of underwear?"

You can't help it; her expression—more scandalised than a friar invited to an orgy at a convent—sends you into peals of laughter. Your mirth is such that you have to hook a foot around one of the desk's legs to stop yourself from falling entirely out of your chair. The privacy ward has to be working for you not to have been confronted.

"Sabetha!" she hisses. "That was mean."

"Good." The words slip out around your chuckles. "You're learning."

You straighten, setting your chair back against the floor.

"Listen, Ruri," you say, looking her straight in the eyes, "you seem to have the wrong idea about this arrangement. I might be a Fallen Angel, but I didn't agree to teach you just because I wanted to keep fucking you. Let's be honest with ourselves here: if I'd refused, and still turned up at your restaurant tomorrow, would you have said no?"

She glances away. You reach over, and tilt her face up by her cheek. She doesn't resist.

"It's not your fault. Most people never get a chance at someone like me, and you seem more deprived than most. If I were in your shoes, I'd be honoured."

"No you wouldn't," she says. "That's what you'd tell them."

It startles a laugh out of you, and your hand drops away. "You're cute when you're cheeky. My point is that you don't need to turn up in half a kimono and nothing underneath in order to keep my attention. You have a lot to learn before you're ready to deal with the sort of people who take advantage of—or want—desperation like that."

"What if I want to dress like this?" she asks; the challenging thrust of her jaw would shame a swordsman.

You shrug. "Then by all means, go ahead. I'd be a little bit of a hypocrite to try and deny you freedom of expression. But I saw the way you glanced around the room when you arrived, and trust me; I know the difference between nervous thrill and nervous discomfort."

Ruri droops a little in her chair, like a plant consigned to shade. "Yeah, you're right."

"Of course I am," you say, because, well, of course you are.

She huffs, amused. "Seriously, though, I'm young, but I'm not entirely naïve. What else do you want from me? Fallen Angels don't do things out of the kindness of their hearts. Even I know that much."

You mind flits—as it so often does—to Azazel. "You'd be surprised."

Just not about me.

"Consider this your first test," you continue. "Figuring out why I agreed."

"How is that related to expanding my supernatural education?"

Your smile would make a shark jealous. "The first truth about a world of gods and monsters is this: when you regard it, you see what others have chosen for you to see. The first lesson is to realise that this is a gift. If everything you see—everything you have ever seen—exists because someone allowed it, then it was allowed for a reason. It exists because something desires it to keep existing. Understand that desire, and you can guess at motivation. Guess at motivation, and you begin to comprehend the one it motivates.

"Comprehend the architect, and reality itself unfolds like the petals of a flower."

Ruri cocks her head to the side. "That sounds like something from a book."

"Maybe it is," you say. "Point is, to figure out the right way to treat a member of the Winter Court as opposed to a Valkyrie, you need to know them. I'm not particularly unusual for a Fallen Angel, so if you want to learn what to do and how to act when you meet another, pay attention."

"Yes, teacher!" She nods firmly.

"Good girl." Ah, there's the pout again. "More seriously, I don't have a list of what you have and haven't been taught about the way things work, so I figured I'd open it up to you. What do you want to learn about first?"