I Want To Suck Your Blood
Vampires must feed on blood; otherwise, they cannot rouse themselves from sleep. They may drink stored blood (such as from a hospital or blood bank), but stored blood doesn’t taste as good or is as sustaining as hot, fresh blood from the source. Weaker vampires can sustain themselves on
animal blood, but it is not as effective as human blood.
Feeding on an unwilling target requires the vampire to grapple the victim; once the grapple is established, the vampire can feed each round as a standard action by making a successful grapple check.
Feeding on a live creature is called the Kiss, and it is an ecstatic experience for both vampire and victim. Once the Kiss begins, a non-vampire target must make a Will save (DC 10 + the vampire’s Hit Dice + the vampire’s Charisma modifier) or succumb to the ecstasy and stop resisting. If the vampire is in combat and feeds on his opponent, the victim never needs to make this Will save and can resist the vampire’s attack every round — no matter how good the Kiss feels, your mortal enemy won’t sit back
and let you do it. Feeding on a willing target (whether a volunteer or one
who has succumbed to the Kiss) is a standard action and requires no grapple check. Each round of feeding on a human subject gives a vampire one Vitae.
A Medium humanoid creature contains enough blood to generate one Vitae per two points of Constitution, and each Vitae a vampire takes from the creature deals two points of Constitution damage. Because Constitution damage heals at a rate of one point per day, and a vampire must expend
at least one Vitae each night he rises, a vampire cannot rely on a single humanoid creature for feeding; the creature gets depleted over several days. Vampires usually rely on more than one source of blood; otherwise, they leave behind a string of bodies that others can trace to them. Medium or larger Animals are worth one Vitae for every four points of Constitution, though each Vitae taken from them still deals only two points of Constitution damage.
A Small creature is worth half as much Vitae as a Medium creature of its type. A Tiny creature is worth one-quarter as much Vitae as a Medium creature of its type; anything smaller cannot give vampires Vitae.
Stored blood has only a fraction of the potency of fresh human blood; a vampire must consume eight pints of human blood to gain one Vitae. A dead human body can provide a single Vitae, and is available as Vitae only within 24 hours of the host’s death.
A vampire may feed on another vampire, directly draining Vitae from her target and adding it to her total. However, feeding this way risks blood addiction and a blood bond.
Vampires have a psychological dependence on fresh blood. Even if the vampire is fully sated on animal or preserved blood, feeding on a live person is thrilling. Every time a vampire feeds on a live human, the vampire must make a Will save to resist draining that person completely dry (DC 10 + 1 for every day that has passed since she last tasted fresh human blood). Most vampires try to feed regularly to stave off this impulse, as a trail of dead bodies draws attention; a rare few avoid feeding on humans entirely.