There are Vulcans Among Us
Came across this account of a man being operated on and the surgeons discovered he had dark green blood!! It turns out he has something called Sulfhaemoglobinaemia where sulfur atoms become incorporated into haemoglobin molecules. I immediately wondered what would happen if a vampire fed on such a person - would it be nutritious for the vampire and/or palatable? I'm such a vampire dork *g*