Why do Twilight vampires have red eyes?

Vampires are meant to drink human blood. It is natural instinct, and most do it. The vampires that refrain from consuming humans and consume animal blood instead are the Cullens; they are the peaceful vampires. Vampires who normally drink human blood have red eyes, and get dull when they become thirsty. read more

In the"Twilight Saga" mythos, vampires with red eyes indicate that the vampire has eaten human blood, which is why James' coven has red eyes as well as the Volturi. If a vampire has only had animal blood ("vegetarianism" as the Cullens say), like Edward's family, their eyes would be golden. read more

The twilight vampires have red eye’s because they drink human blood, some vampires like the Cullen's have yellow eyes because they drink animal blood, the brightness of the colors of their eyes depends on when they last fed. read more

Twilight Vampires have red eyes only if they drink the blood from humans. When they drink the blood, their eyes become a crimson like colour. The longer from the feed, the lighter red their eyes become. read more

Vampires in Twilight have red eyes because that’s what author Stephenie Meyer imagined and wrote. She fleshed that out by giving the “nice” vamps yellow eyes that weren’t inflamed by human blood. Last time I checked, most animals (mammals) had red blood, too. Hey, it’s supernatural so let’s not be a stickler for facts. read more