"They're not vampires. They can't manufacture hemoglobin, so the quickest way for them to maintain homeostasis is blood. The adrenal glands are misfiring, granting incredible speed, strength, and disregard for pain. The paleness is a function of constricted blood vessels. The extreme photophobia is the organism itself; it lives just under the epidermis and can't handle ultraviolet radiation. So they're not vampires. They're infected with aphotic hemophagic adrenal anemia."
"But see, if I'd been able to shout, 'Look out! Vampire!' instead of all that gibberish, you'd have been able to look up in time to not get eaten just now."