"There's a lot of books like this here," she remarks as he stamps them for her, just this side of audibly. "I don't think my old school had any..."
The persona she is attempting to wear does already know about magic and vampires and the like (by observation and rumor, not by Power visitation), and is trying to find out if Mr. Giles does too.
"Do you believe in magic?" she blurts. "I think I do - I didn't before I moved here - but I think it might be real, at least some of it, even if I can't make anything in the books work and can't find anyone else who can either -"
(She would like him to determine that she is good-hearted and naive and in need of a decent teacher before she finds an indecent one.)
And he reaches under the counter to pull out a stack of dusty-looking old books with extremely similar cover designs.
Bella takes them eagerly and looks for indices. "Do these have some kind of - introductory material - I haven't been able to get anything to work," she says. "I think I'm missing something very basic."
"Well," she says. "This explains all the suspicious barbecue fork deaths after sunset much better than drugged gangs who use cooking implements as weapons."
"I... actually already guessed," Bella says sheepishly. "If you look at my borrowing history... I didn't get these books exactly but I've gotten others that mention vampires and I didn't think it was smart to take chances, given all the funny statistics. I replaced my porch lights with those sunshine bulbs and know not to invite anyone into the house." If he agrees to teach her anything she'll also tell him about covering the town in crosses and her key to the morgue.
"Yeah. My dad and some other cops had a standoff with some folks who had oddly colored blood, a while ago. And Sunnydale has a pretty bad rate of unusual occurrences even when the sun is up. But I haven't found anything so straightfoward about how to deal with those. Have these books got instructions? Stars of David and maple syrup instead of crosses and holy water?" She flips through one of the books, treating the pages gently. "Because otherwise I think it comes back to magic."
He's sounding crustier by the second.
"Magic is addictive?" Bella asks skeptically. "Literally, or is that a metaphor for it being useful or fun to the point where using it leads to using more by some mechanism that is not, literally, addiction?"
(If he were bullshitting her he probably wouldn't have said it was rare, so she's going to take this as likely accurate, and something she needs to find out about before attempting to learn anything.)
"Is there anything else you can tell me besides recommending the books? Are these even..." She looks at the spines. "They're not library books. Can I borrow them anyway?"
This is probably all she's going to get out of Mr. Giles. At least this time. What a pity. (And he knows some magic, too, if he fixed the cheerleader, as seems likely. Frustrating.)
She takes the books. She spends the rest of her study hall reading through the first chapter of one, taking notes, and then she goes to the rest of her classes and hangs out in the library to continue.