After school, she hits the library. They have a rather impressive collection of suspiciously elderly and internally consistent books on vampires, their lacking of souls, and how to kill them. It also explains where they come from.
Bella realizes that tangling with any of these creatures will put her life at risk. She orders a repeating crossbow online from an obscure custom weapons manufacturer, and a make-your-own-bolts kit, wiping out her savings in so doing - but that's not the best approach, she thinks, that shouldn't be her first line of defense.
Her first line of defense, besides wearing a pretty golden crucifix that Renée left behind when she moved out of the Sunnydale house and acquiring enough holy water to rinse her hair in it after every shower (it's more effective wet, but leaves a trace dried if it's not washed away by something else first), is this: She walks into her dad's bedroom on her hands, does a roll and a flip and takes a bow, and says, "Dad, I need a key to the morgue."
Barbecue fork deaths usually pass through police hands, and just as usually they never find anything. If she goes once a day, finds the autopsied bodies, and drives even just a sliver of wood through their hearts, they'll puff into dust before they can claw their way out of their graves later. She doesn't think this will eliminate the vampire population of Sunnydale, but it will certainly curb it without the least bit of danger to anyone.
Charlie stares at her. He says, "Why's that, Bells?"
"Barbecue forks," she says, "have a way of multiplying. I have a way of sterilizing them."
He stares at her a bit more. "Let's see that flip again," he says slowly.
She flips, obligingly. Twice.
Three days later she has a key to the morgue. She doesn't ask him how he got it. He doesn't ask her why she can do gymnastics now. He tells her when the place is usually deserted and she tells him thanks.
She gets a package of firewood, splits it into splinters that are pointy at one end and too wide to pierce her hand on the other, and diligently renders everyone - no point in skipping the non-barbecue-forks; for all she knows there are lesser-advertised ways to become a vampire, or less popular blood vessels that work just as well as the classic neck ones - unable to rise with the third night of their demise.
Nighttime deaths drop. After two weeks it's enough for Charlie to notice on his statistics.
He takes her out for ice cream and says he hopes she's not up to anything dangerous.
She's not, then. She says,
The next day, her crossbow arrives, custom-made and shiny and the right size to hide in a messenger bag. She goes to a little woodsy spot, twenty minutes' drive away, and shoots at knots on trees and confirms that she's got herself decent aim. She makes herself a great big stack of ammunition, which she keeps discreetly in her closet but not actually hidden. Charlie is not a snoop, and it's not so much a secret from him as it is a vaguely impolite topic.
She starts patrolling after dark, and Charlie furrows his brow and frets but doesn't remind her pointedly about her curfew.
The first vampire she finds is being ludicrously obvious about it, walking around with his fangs out. She gets him from ten feet away -
And she drew her bow at six yards.
She needs to get faster. She has none of that sensory mojo the Power That Was In Her Bedroom advertised.
She reads. She practices drawing and shooting and loading a new packet of homemade bolts, and she makes stakes and holy water balloons and learns to throw them, and she watches people on the Internet do aikido and shadowboxes them the second time through each video. She replaces the porch lights with sunlamp bulbs; she's not sure if that will work but it can't hurt. She escorts fools who are out late to their homes, when they cross paths with her. (Her excuse? Her dad is the chief of police, and even gangs on PCP know it and will steer clear of her.)
She leaves crosses around. By "around" is meant "hiding". Under sidewalk pavers, where they come up enough for her to jam one underneath. Scratched into the underside of the pokey bits of fire hydrants with a screwdriver. Cut unobtrusively into paper snowflakes and hung from the tree in the elementary schoolyard with a hundred others. Drizzled in white paint on white lines or black paint on sections of asphalt filler in the crosswalks. From what she has read, only direct contact with a contiguous object that is a cross will burn a vampire, and her little traps won't do them any injury at all - but as deliberately made crosses and not accidental line intersections made without intent or for other purposes, they will nevertheless cause a subconscious aversion. She memorizes where they are and she watches who walks right over or past them - and whose path wobbles, whose step falters, who looks suddenly like they are in a bad mood. The latter sort she follows. About half of those are coincidence - they wind up walking unimpeded into private residences or having no reaction to the next cross they pass - and half of them she catches trying to eat somebody. And shoots and dusts.
She's laying down hidden crosses in a neighborhood she hasn't covered yet at just past eight p.m. when she spots a person about her age, maybe a little older with that posture. And since she hasn't covered this neighborhood yet he isn't wandering over any of her little traps.
Well, as far as she knows, most people in town are human; the odds are in his favor. "I don't recommend being out at night hereabouts," she calls. "I don't count, my dad is chief of police and everybody knows it, but you probably wanna go home."
"I am an outlier," he agrees. "In more ways than you know."
"Yeah? What else?"
"Nothing I particularly care to tell someone who is half convinced I will spring for her throat at any moment," he says pleasantly.
"At this point I wouldn't describe myself as convinced, just possessed of a certain amount of background knowledge," says Bella. "You wouldn't like the condiments I put on before I go out, though."
"You are a continual delight," he remarks. "And among many other reasons why you have nothing to fear from me on that score, I only eat people who bore me. You do the opposite."
"So what I'm hearing is that I need to make sure I'm in a private residence before running out of material, is that right?"
"Not only am I not eating you," he says, "I am currently not eating anyone else, purely because I expect it would annoy you. Hence the shopping."
She closes it.
"That's interesting," she says finally. And then, because she doesn't want to be tricked, because vampires are tricky, she continues, "that you call it shopping."
"A regionalism, where you would say 'groceries'. Or did you mean my drawing the analogy in the first place? I think it's funny."
"I mean you didn't shop for it so much as swipe it. Do all butchers have blood in the back room?" she asks, looking dubiously at the establishment. "I wouldn't think there would be much call for it. Even among vampires, who normally prefer the other other white meat."
"...Are you not aware of the seedy little demon bar operating in your town? It's called Willy's," says Sherlock. "It's atrocious. Never combine cold pig's blood with warm vodka. I am unutterably enthusiastic about stealing from their supplier given the sins they commit with their stock."
(She's not going to go check it out right away even if he gives her the address, password, and a sealed package of crossbow bolts. She is not that good yet, there could be dozens of hostile creatures in a demon bar.)
"I could show you," he says. "But, reasonably, you don't trust me."
"I'm so glad we agree on my reasonableness," she says dryly. "You could tell me where it is, in case I need to know later."
"End of the alley halfway between Walnut and Elm Grove on Reicester. Pity, I was hoping to see your face when you witnessed your first game of kitten poker."
"...Kitten poker," says Bella.
"Both as adorable and as horrifying as it sounds."
"What does one do with accumulated kittens?"
"If one is the right sort of demon, one eats them; otherwise one trades them to same. Or admires their fluffiness, I suppose. I've never seen the point in any of the above, myself."
(This is clearly a joke. She is joking with a vampire. Why is she joking with a vampire?)
"You wound me, madam."
"Nah. I tried, but I don't seem to be ready for the Olympics yet. And it's such a shame, too, I wanted to represent my country and take home the gold," she says earnestly.
"Ah, yes. A Slayer with a distaste for close combat. Will wonders never cease."
"Turns out vampires tend not to rise from the grave with ranged weapons equipped. Why would I want to engage in close combat? Do most Slayers prefer it? Geez, how long do they live?"
"Twenty-six is the record, I believe."