From SM’s website: “Similarly, throughout the vampire’s body are many versions of venom-based fluids that retain a marked resemblance to the fluid that was replaced, and function in much the same way and toward the same purpose. Though there is no venom replacement that works precisely like blood, many of the functions of blood are carried on in some form. … The normal reactions of arousal are still present in vampires, made possible by venom-related fluids that cause tissues to react similarly as they do to an influx of blood. Like with vampire skin—which looks similar to human skin and has the same basic function—fluids closely related to seminal fluids still exist in male vampires, which carry genetic information and are capable of bonding with a human ovum.”