What is a Buffy vampire?
It's a human possesed by a species of demon. The physical effects are to make you an animated corpse. You still have to eat, or else you waste away like a living human, but most of the signs of life are absent. You have no heartbeat, no need to breathe, although that's such a strong instinct that you'll find yourself going through the motions anyway, especially when very active. This of course is bollocks. I'd imagine vampires would exalt in their freedom from these constraints. It's just a way of explaining why the actors are breathing hard.
The demon has little or no personality of its own, so it uses yours as a template, keeping your memories, but removing your soul.
How are you made into a Buffy vampire?
A vampire bites you, it then cuts itself, you are overcome by a compulsion to drink its blood, and you become a vamp. This method takes a few hours to work, as seen in (Helpless).
Alternatively, the vamp drains all your blood, and you die. A day or so later, there is a small chance you awake as a vampire, and dig your way out of the ground. The delay is variable, sometimes the body awakens before the funeral(Theresa in Phases), but most of the time, you're just dead full stop if you've been drained.
What's a Sire? The vampire that turned you is called your sire. Vamps are usually choosy about who they make a vampire. Most of the time you are merely fodder. When you are turned, your sire sometimes trains you in being a vampire, how to evade detection, how to fight etc.
What is a Soul in the Jossverse? Your soul is the collection of emotions that we consider human, things like love, guilt, compassion, consideration etc. These are the emotions that are on a higher plane than the base ones such as anger and jealousy. These are the product of the physical brain, an animal's organ. The benign emotions are artificial in the sense that they require a self-aware personality to exist. When you lose your soul to a vampire demon, you cease to be you, since only the animal emotions are left, coded in the physical neural pathways in your brain. There are exception to this: Lyle and Candy Gorch, and of course, Spike and Dru, showed a whole lotta love for each other.
What kills Buffy vampires?
Vampires can be damaged by anything that'll hurt a human, allowing for the fact vampires are physically much tougher than humans, but can only be killed in a few ways;
In order of instant deadliness:
Beheading.
Quite rare on Buffy, but when Giles killed one in Bad Girls with a sword, it was more or less instant.
Wood through the heart.
Anything from a pencil (Choices) to six foot long piece of timber (Faith, Hope and Trick). Kills instantly in the case of weak vampires, but there's enough time for a snappy line for a stronger one.
Sunlight and Fire
In both cases, the vampire has a few seconds to get out of the fire/light before he dusts. It seems fire is even deadlier to a vampire than to a human.
Holy Water
It burns like acid, but the only kill on record is Zachary "Bow Wow" Krane. And he drank a whole bottle of it, which took around ten seconds or so to dust him.
Crosses
Never seen a kill with one, but I suppose if you strapped one to a vamp it would dust it after a while.
What's the Jackanory with Mirrors and So On?
Vamps have no reflection, in any kind of shiny surface. Mirrors, polished metal, the lot. If you see one, it's a cock-up
They do show up on camera, and they do cast shadows.
How do Vamps do their hair? You know that white screen in Angel's mansion? He stands inside that and uses his shadow, and lots of nancy-boy hair gel, to style it.
Is the Fonz a Vampire? Yes, I'm afraid so. First off, look at all the leather, plus the bit in the opening credits of Happy Days clearly shows him walking up to a mirror, spreading his arms in surprise, and going "Hey, Mr C, where's my reflection? Heyyy!"
Do vampires eat anything except blood? A couple of lines cut from an season 1 or 2 show:
Buffy: So, do you eat?
Angel: Yes. Not for nutritional value. It just kind of passes the time.
This line might have been cut so Joss could leave that one open.
Vampires also eat raw meat, usually that of their victims, but that again is for fun. I decided that vampires would vomit if they ate cooked meat or vegetables, so I put that in my fanfic. I made that up though. Spike likes to crumble Weetabix into his blood as a thickener, which doesn't entirely contradict my take, the bulk of his meal still being blood, so I left Slayer-Vampire-AnotherSlayer Xander vomming after crisps in.
Why are some vampires so much stronger than others? The Master, Spike and Dru, Angel, Kakistos, and Evil Willow were all much stronger than the run of the mill vamps. Some of that will just be down to the fact some people are simply better at fighting than others, and that's that. On top of that, if your sire has been around for a while, he/she will have taught you well, Obi-Wan. There's repeated reference to Angelus being Spike and Dru's lecturer in Inventive Bastardry for Beginners. That certainly would have helped them get so nails.
talliscanon has the theory that the physical strength of a vampire is determinedby the intelligence of the host:
I personally reckon that some people mesh well with their demon, and it's just a random accident of birth and personality, the same way that some people just happen to be good at chess. Some people have a talent for languages. Others are good at being a smartarse specky twat. Like me.
Being clever helps, since it gives the demon plenty of material, a stupid host doesn't preclude a good vampire, but a really hardcore vamp needs a brainy host.
If you look at Lyle Gorch, he was thick as two short planks, but he gave a good account of himself to Buffy,admittedly helped by his brick shithouse build.
Angelus was too busy being a drunken waster to be clever, even though he wasn't intrinsically stupid, but he meshed so well with his demon that he became the second hardest vamp ever.
I reckon Spike or Dru did sire Billy Fordham, purely because Spike would keep the food for himself or Dru, especially since he didn't know how long they'd be in the bombshelter.
Ford didn't click with his demon, so Buffy Vs. Ford was the greatest mismatch since Bobby the Cuddly Butter Man fought Vicious Vinny Hotknife, the most feared warm item of cutlery in all of Christendom.
I go with the idea of inherited hardness, mostly because I like it, but also because Spike, Drusilla, Penn, and Angelus were so much nailsier than all the other vamps we see, even on top of training and other external factors. I assume the run of the mill vampires were trained by the Master, Angelus, etc. but they weren't sired with the stones to compete with Peroxide Boy, the Killer Mick and Baquette Woman
Who's the strongest vampire the show has seen? Willow was seriously intelligent, she was Yoda'd by the Master, who probably sired her, so her personality gelled with his very strong demon, so she had all four component of a strong vampire. Hence she is The Man of the vampire world. Except she's The Woman.
What about demons? How many of them are they?
Several thousand species, most of which have a gimmick, like vampires' staking and lack of reflection. This allows Joss and Co. free reign to make up any kind of beastie they want. Hooray!
In order to exist on the Earthly Dimension, demons have to taint themselves with an existing Earth creature, the way vamps do with humans, or Machida the Reptile Boy did with a snake. Under very special circumstances, the only example given is the Mayor's Ascension, a demon can exist in pure form on Earth. This makes it much bigger and more powerful. Shite.
Luckily, an Ascension is such an elaborate ritual it took the Mayor, apparently a very powerful black magicker, over a hundred years of demon tributes and soul selling to acheive.
What about slayers? My take on Slayers and all their baggage is this:
1: There's some kind of Slayer mojo thing hovering around on Earth.
2:At the dawn of time, when the last demons were being booted out by the good bouncers of Planet Earth (see Welcome to the Hellmouth), the mojo manifested itself in an adolescent girl, to kick seven shades of shit out of the demons that were left.
3:The effect of the mojo was to make this wee girl hard as nails. And sometimes,
depending on the girl, give her prophetic and/or magic sensing abilities known as :
4: Certain girls were born unusually mojo-friendly, in the same way some people pop out the womb resistant to certain diseases. They would remain so until some point in adolescence, at which time, they would cease to be a Slayer-in-Waiting. Why do I think this? In Helpless, we are told the drug is given when or if they reach their 18th birthday. No mention is even made of anyone being called after this. The slayer is always described as a girl, never a woman, and the only slayers we've ever heard of are Faith, Kendra, and the Korean Chick from Puppet Show, who was described by Sid the puppet as pretty young. And she could have been the Slayer for years, if she was carefull enough.
5: After awhile, the slayer would get topped, or just die of old age,and the mojo would transfer to one of the girls that were compatible. This process happened at random, amongst the girls.
6:At some point much later, some anally retentive Britons, wearing a early form of tweed, noticed there was a wee girl doing damage to demons. They approved,drank a lot of primitive herbal infusions , and decided to look after her, and study the buggers she killed.
7: Later, they worked out point 4. They decided to dedicate one of their number to each of these girls, to train her from an early age so that if she was called, she would be pretty handy in a swedge.
8:They then discovered an ancient herb called "tea" and chose it as their herbal infusion of choice.
9:They then realised that the stable of girls that were mojo-compliant were distributed entirely at random throughout the world. They would then have had to expand, first off to supply each girl with a Watcher (we are never told how many there are), and secondly to find the girls in the first place.
10: The Council discovered a magical way of telling who was a SiW (Slayer in Waiting)
11. The reason we never heard about this magical SiW Detector is that it was an exceptionally well kept secret. Even Giles doesn't know. In fact especially Giles,with his murky past. The SiW's are finite in number, and this number is due to entirely random genetic chance. If some evil chaps and chapesses got hold of the Detector, whatever or whoever(maybe it's a Doyle demon), it is, they could kill off all the Slayers in Waiting. If the existing Slayer was killed, there would be no vessel for the Slayer mojo, and it would fizzle out. World Doomage ensues.
12:The Detector didn't work that well(makes sense if it's a Doyle demon, he gets pretty vague visions), so Buffy wasn't found until she was sixteen. This makes sense, since modern life has people moving around a lot more, and over greater distances. As it happens, Buffy was the Slayer by the time she was found.
13:Buffy died for around two minutes. This caused the Slayer mojo fairy or whatever to move to Kendra, who had been found earlier, because she had kept still long enough to be found. Or/also, her family are apperently into hoodoo mumbo jumbo, and had the secret of the SiW Detector already.
14:Buffy is revived by Xander. The mojo no longer thinks she is the Slayer, but she keeps her strengths and the Wiggins anyway.
15:Kendra is killed by Dru. Faith was an SiW, but moved around like blazes, so wasn't found until she was a Slayer. Which makes me think:
16: The Detector works much better at finding an actual Slayer, or there is a different, more efficient, Detector for them.
What Kills Werewolves? I'm making this up, but Cain the werewolf trapper used silver bullets to hunt Ozwolf, and Ozwolf killed Verucawolf, so I say only silver or a werewolf can kill a werewolf. They'll be some way of blessing a normal object so it can kill them, but why arse around with Wiccan stuff when you can just silver-electroplate a tank?