Yellow Eyes

Some vampires, unlike Victoria's army, drink the blood of animals instead of humans. Carlisle Cullen's coven does this, as Carlisle does not like violence that can be avoided. If a vampire does this, their eyes turn a warm golden yellow instead of the shocking red that is on normal vampires' irises.

This allows these vampires to fit in with humanity, which isn't easily done. The whole time these 'vegetarian vampires' are among humans, their throats burn with an unnatural thirst. But the Seattle Newborn Army doesn't bother to try this. The humans that they see all die. When Riley describes the Cullens to the newborns, he calls them 'strange yellow eyes', and says that they are old and weak. However, this proved to be a lie, and every newborn was killed.