"...Have you ever done a study, on, like, non-Christian vampires, if this is possibly belief related?"

"We haven't.  It may be an interesting avenue of research.  But the common wisdom is that - "  He frowns pensively, composing his thoughts.  "You might say that crosses are harmful to vampires, not because the vampires are Catholic, but because vampirism itself is Catholic, as it were, and so the beliefs of the individuals afflicted with it would make no difference.  If that makes... any sense at all."

"...I'm not. Like. Good enough at puzzles to figure out the weird stuff that implies about magic."

"Oh, one can make a life's work out of deciphering this sort of thing.  ...I do have a diagram I could draw you, if you think that would help."

"Heh. Maybe leave that to my friends. They're all smart-like."

"We may be getting a bit off-track," Giles admits.  "I was explaining vampires' strengths and weaknesses."

He goes through the rest of it.

"Kind of feels very - like I bet I could've guessed most of that just knowing about vampires, but it sounds like vampire myths are older than vampires? Which is weird?"

"There are schools of thought which suggest that the forms that dark creatures take are influenced, either directly or indirectly, by preexisting myths."

"Weird."

"Quite so."

"Now," he says, "Miss Uzun, we should schedule a regular meeting time for you to spar and study vampires.  Ideally the Slayer should practice every day, but then in an ideal world she would not be recruited at random from the ranks of fifteen-year-olds," he says dryly.  "What would you say to meeting with me once a week, and choosing from among my recommendations a mundane self-defense class to attend regularly?"

"It's probably better for me to be able to use my full strength when practicing, isn't it? Like, if there's a slip at the self defense class, that's a whole class who might've noticed something's up - and I won't have a good sense of my strength if I don't use it. Honestly, I'm already good at self defense - practicing against my demon friend to apply that to new superpowers would be good, and otherwise I need to get used to moving around. Like the parkour I was practicing, and that I can do every day easy."

“My plan had been to arrange for a private tutor, but that is a fair objection in any case. How about you and your - demon friend, I don’t believe you mentioned their name - meet with me after school twice a week, then?”

"Twice a week works just fine. I'll have to ask her about whether she wants to come along, though."

"Well, fair warning, you'll have to spar with me otherwise."

"You any good?"

"I know the, ah, theory."

"Maybe I can train you."

"Oh, I'm sure I have... knowledge to impart.  I just may have you try it out on the training dummies.  I am unfortunately an unaugmented human."

"You're doing really well as the super secret agent guy!" 

"I'm pleased to hear you think so.  And I'm glad you're already looking for ways to get the most out of your training.  It's a habit that will serve you well as Slayer."

"I like making the most of things! It's fun."

"A useful hobby for a Slayer to have."

He does recommend a self-defense class, but for Tag and Kaylee rather than Nausicaa; and then retrieves a few volumes about vampires (smaller, more recently written, more accessible than VAMPYR) to lend out to Nausicaa for study.

Great!

...She's guessing there's no vampire audiobooks. Well, she'll just have to struggle through these between textbooks, maybe.

"I can look through them too, if you like, I'm good at research.  I'll have to keep them hidden from my parents, though, unless..."

She takes a breath.

"Mr. Giles, I'd like to - make my pitch for telling my parents about this.  I understand why it's a bad idea to tell other kids, even if I trust them.  But my parents are different, they're going to be able to tell that something's going on with me, I'm not sure I could keep it totally secret no matter how hard I try.  And I'm sure that... if I couldn't convince them not to tell anyone else, if I got them in a room with you, you could."