Dude, my accidental headcanon for years was that the, ahem, vampire sexual fluids were actually blood, since it seems to replace all the other fluids. I forgot the “the lower parts doesn’t work anymore” part and, by my logic, if they cry blood -> they also sweat blood -> so they must split blood too, then -> WELL… (It also would explain why vampires love red sheets and basically red everything in home decor)