Vampires are undead: literal walking corpses held together and animated by supernatural powers.
A vampire sustains their unlife by drinking the blood of mortals. This act does not, by itself, create a new vampire.
To create a new vampire, a mortal must be Embraced by another vampire: After completely draining a mortal of their blood, the vampire must then give them a drop of their own Blood, beginning the transformation process from dead to undead.
Vampires are immortal. As long as they keep drinking blood, they'll keep unliving.
Things like knife wounds, gun shots, bites, and scratches will hurt like hell but won't seriously harm a vampire in small doses.
Vampires are deathly allergic to sunlight and fire. Direct exposure will lethally burn them.
Vampires need 'daysleep' and find it very difficult to stay conscious while the sun is up, even if they can't see it.
Being dead, vampires have no need of food or drink (other than blood). Attempting to ingest food may result in immediate vomiting.
Vampires have fabulous secret powers that allow them to do things mortals cannot.
You will discover many other perks of vampire unlife along your journey.
A vampire's Blood is different from mundane blood. Blood is all that keeps a vampire's body from falling apart and decaying into dust. It magically grants vampires their unlife.
Vampires use a little Blood every night to wake up and to fuel most of their supernatural powers.
Mundane blood is transformed into supernatural Blood in a vampire's body when they drink it.
Live mortals are the best source. Bagged blood and animal blood aren't as filling and tend to be joylessly tasteless or even foul.
Blood is incredibly potent and addicting. It can even temporarily grant a fraction of its owner's powers to anyone who consumes it.
Drinking someone's Blood too often will form a Blood Bond in which the drinker becomes fanatically loyal to the donor. Only by abstaining from drinking their donor's Blood for many months can this bond be broken.
Drink responsibly.
If Blood is a vampire's fuel, the Beast is their engine.
Every vampire harbors a Beast inside them that, like a wild animal, is primarily driven by fear and Hunger.
Fear drives the Beast away from things like pain, fire, and destruction of the self. Hunger drives it to commit unspeakable acts in states of Frenzy to satiate itself.
Some vampires cling to what remains of their humanity and try to suppress the Beast. Most simply learn to coexist with the predator within them.
Part appetite, part lust, and part addiction, Hunger gives voice to the Blood and claws to the Beast.
Vampires awaken every night feeling at least a slight pang of Hunger. This feeling grows the longer they go without feeding or the more they use their supernatural powers.
The Hungrier a vampire gets, the easier it becomes to lose control of their ravenous Beast. A starving vampire has more in common with a rabid wolf than man. Hungry vampires will find it much more difficult to resist Frenzy.
Frenzy is a constant threat to the fragile peace of vampires. Outside circumstances usually provoke a Frenzy: the death of a friend, public humiliation, the sight of an open wound, or a roaring bonfire might set off a Frenzy. The ultimate expression of the basest drives of the vampire's curse, a Frenzy looses the Beast without thought or remorse: the predator unleashed.
A vampire in Frenzy loses the capacity for rational thought and becomes driven solely by rage, starvation, or terror. They will do whatever it takes to rip the source of their provocation to shreds, slake their Hunger, or escape the perceived threat. Usually violently and with plenty of collateral damage.
A vampire must rely on their Willpower to attempt to resist a Frenzy, should they choose to do so. Some vampires, however, have learned to "ride the wave" during a Frenzy, voluntarily allowing it to happen and using it to their advantage in creative, bloody ways.