"A creature's spit can say much," Thrawn pointed out. "Some beings have venom in their saliva, or hallucinogenics. The reading of your spit shows that your body contains a protein that keeps blood from clotting, presumably for easier drinking."

There was also the numbing agent, which implied that vampires could stealthily bite their victims. Or that they could make their bites hurt less for someone willing, and thus encourage the person to let the vampire bite them again.

"You prefer the blood of thinking creatures, and I would like to find a solution that would please you. That includes offering up myself, because a leader shouldn't make their subordinates do anything they themselves are not willing to."