Thud! by Terry Pratchett

vampire.
    They looked at each other, both aware that this was not going well, both uncertain that they could make it go any better.
    “So…‘Sally’…you want to be a copper?” said Vimes.
    “A policeman? Yes.”
    “Any history of policing in your family?” said Vimes. It was a standard opening question. It always helped if they’d inherited some idea about coppering.
    “No, just the throat biting,” said Sally.
    There was another pause.
    Vimes sighed.
    “Look, I just want to know one thing,” he said. “Did John Not-A-Vampire-At-All Smith and Doreen Winkings put you up to this?”
    “No!” said Sally. “I approached them. And if it’s any help to you, I didn’t think there’d be all this fuss, either.”
    Vimes looked surprised.
    “But you applied to join,” he said.
    “Yes, but I don’t see why there has to be all this…interest!”
    “Don’t blame me. That was your League of Temperance.”
    “Really? Your Lord Vetinari was quoted in the newspaper,” said Sally. “All that stuff about the lack of species discrimination being in the finest traditions of the Watch.”
    “Hah!” said Vimes. “Well, it’s true that a copper’s a copper, as far as I’m concerned, but the fine traditions of the Watch, Miss von Humpeding, largely consist of finding somewhere out of the rain, mumping for free beer ’round the backs of pubs, and always keeping two notebooks!”
    “You don’t want me, then?” said Sally. “I thought you needed all the recruits you could get. Look, I’m probably stronger than anyone on your payroll who isn’t a troll, I’m quite clever, I don’t mind hard work, and I’ve got excellent night vision. I can be useful. I want to be useful.”
    “Can you turn into a bat?”
    She looked shocked. “What? What kind of question is that to ask me?”
    “Probably among the less tricky ones,” said Vimes. “Besides, it might be useful. Can you?”
    “No.”
    “Oh, well, never mind—”
    “I can turn into a lot of bats,” said Sally. “One bat is hard to do, because you have to deal with changes in body mass, and you can’t do that if you’ve been Reformed for a while. Anyway, it gives me a headache.”
    “What was your last job?”
    “Didn’t have one. I was a musician.”
    Vimes brightened up.
    “Really? Some of the lads have been talking about setting up a Watch band.”
    “Could they use a cello?”
    “Probably not.”
    Vimes drummed his fingers on his desk. Well, she hadn’t gone for his throat yet, had she? That was the problem, of course. Vampires were fine right up until the point where, suddenly, they weren’t. But, in truth, right now, he had to admit it: he needed anyone who could stand upright and finish a sentence. This damn business was taking its toll. He needed men out there all the time, just to keep the lid on things. Oh, right now it was just scuffles and stone throwing and breaking windows and running away, but all that stuff added up, like snowflakes on an avalanche slope. People needed to see coppers at a time like this. They gave the illusion that the whole world hadn’t gone insane.
    And the Temperance League was pretty good and very supportive of its members. It was in the interests of all members that no one found themselves standing in a strange bedroom with an embarrassingly full feeling. They’d be watching her…
    “We’ve got no room for passengers in the Watch,” he said. “We’re too pressed right now to give you any more than what is laughingly known as on-the-job training, but you’ll be on the streets from day one…er, how are you with the daylight thing?”
    “I’m fine with long sleeves and a wide brim. I carry the kit, anyway.”
    Vimes nodded. A small dustpan and brush, a vial of animal blood, and a small card saying:
Help, I have crumbled and I can’t get up. Please sweep me into a heap and crush vial. I am a Black Ribboner and will not harm you. Thanking you in advance.
    His fingers rattled on the desktop again.