What is Vampire? part 2

Eyes

"I saved his eyes for last, knowing that when I looked into them I was likely to lose my train of thought. They were wide, warm with liquid gold, framed by a thick fringe of black lashes. Staring into his eyes always made me feel extraordinary-sort of like my bones were turning spongy. I was also lightheaded, but that could have been because I'd forgotten to keep breathing. Again."

―Bella Swan

A comparison of the eyes of two vampires: the red (Aro) are of a vampire who feeds on humans, and the golden (Jasper) of one who feeds on animals.

A vampire's eye color changes with both his/her age and diet. Newborn vampires show bright red eyes; a diet of human blood would darken them to a rose red color. However, a diet of animal blood would instead dilute the eyes to a golden color. Thirsty vampires show dark, onyx black eyes.
Only the Cullens (the Olympic Coven) and the Denali Coven are known to be vegetarian vampires, feeding only on animal blood. Their eyes are liquid topaz, or honey-golden, reflecting their diet. These eyes, however, are viewed as strange and somewhat unnatural by other vampires whose diet consist of human blood, such as James and Victoria, and whose eyes are of a vivid deep crimson, becoming even more vivid as they continue to feed on human blood, and a darker burgundy as they abstain. Newborn vampires are known for having incredible strength as well as brilliant crimson eyes. Bnth traits are caused by their own blood that still lingers within their tissues, producing the shockingly bright red eyes that "fade slowly over the course of a year" and incredible strength.
Meyer writes that, if a Cullen were to drink human blood, his/her eyes would instantly turn burgundy, and if two weeks were to pass without blood, his/her eyes would grow dark. If he/she were to return to a diet of animal blood, his/her eyes would become dark gold, and a lighter golden color, if they were to continue on animal blood. As a vampire's thirst grows, his/her eyes grow darker with it, until they at last become a coal black. In contrast, as vampires feed, their eyes become lighter. In addition to the thirst, the purplish-black bruises under their eyes become more pronounced as their thirst grows. Though if they have recently fed the bruises becomes less noticeable, and all but disappear (depending on how well-fed they are). The bruises indicate that vampires never sleep.

Teeth

A vampire's teeth appear no different than regular human teeth. They do not possess fangs. However, a vampire's teeth are flawless, unbreakable, and razor sharp at the edges. They are also incredibly strong, able to bite through almost any solid substance including vampire skin. On her first hunt as a vampire, Bella describes biting through a mountain lion's neck like biting through butter.

Abilities and limitations

A vampire's physical and mental abilities far exceed those of a human being. These traits vary between different vampires depending on what they were more capable of as humans. Certain vampires also develop one extra supernatural power that is developed from his strongest trait as a human.

Speed

Vampire (Victoria) running so fast she becomes blurry.

One of the most amazing among their abilities is their speed. They are able to run in excess of a hundred miles per hour, substantially faster than the human eye can see. When vampires run, they become "all but invisible". The Quileute wolves are noted to be one of the few things that can outrun them. This suggests that vampires are meant to move to a new location every so often. We see the speed of all the Cullens again during the baseball game. Emmett is described as "a blur around the bases", and Edward can move so quickly that he is able to intercept a ball that has been hit "like a meteor."
They can lay down and sit up within the same second, almost without having to even think about going through the motions. After being turned into a vampire, Bella describes her movements as being instantaneous.

Strength

"You are so soft, so fragile. I have to mind my actions every moment that we're together so that I don't hurt you. I could kill you quite easily, Bella, simply by accident... I could reach out, meaning to touch your face, and crush your skull by mistake."

―Edward to Bella on his strength

Ddward exerting his strength to save Bella.

Another enhanced trait is their unstoppable physical strength. A vampire is said to be thousands of times stronger than any human, able to lift objects hundreds of times their own weight. Edward feared his strength when first meeting Bella, and explained that there was barely a difference to him in strength between caressing her head and knocking it off. A good example of their strength is seen when Bella decides to arm wrestle Emmett after becoming a vampire. She describes the power in his one arm to be about the same as a cement truck moving downhill at over 60 miles per hour. She beats him, however, because she is a newborn at the time. Newborn vampires are always stronger than older ones, since their strength derives from the lingering human blood left in their body. Diet does not have a massive impact on strength, since it always depends on the individual vampire. A vampire's strength also enables them to leap incredible distances. Edward was able to leap over a 50 yard wide river with ease during Bella's first hunt as a vampire, while Bella was able to leap over twice his distance, while only using slightly over half of her full force.
A diet of human blood makes a vampire stronger than animal blood (though only fractionally). Vampires who feed on animal blood (vegetarian vampires) find that "big game" - predators like bears or wildcats - not only smell more appealing to them, but also make them stronger than the "weaker" blood of herd animals such as deer or cattle. Strength, of course, is not always physical. If a vampire possessed great mental strength and willpower as a human, he will find it easier to control his wild, animalistic instincts. Even so, if a vampire has not fed for a long time, he will be less likely to think clearly and more likely to give in to their thirst, attacking the first living thing he detects and draining it of blood within seconds, all without a single thought (human or animal). If, however, an unlucky human were to be near their vicinity, they will preferably attack him/her rather than the animal.

Senses

Bella exploring her new senses as a vampire.

A vampire's senses (smell, sight, hearing, etc.) are also greatly enhanced, which enables them to see, hear and smell things imperceptible to humans. While running, a vampire can see and sense everything that is around them, making him able to keep tabs of their surroundings and avoid hitting anything unnecessarily. Their sense of sight exeeds by far that of a hawk.
When a vampire hunts, he uses his sense of smell to find a prey and hearing to track its movements. Smell is most intense to vampires, since he can smell the blood of his prey.

Special Abilities

"Yes, well, there are some vampires who have gifts beyond the usual super strength and super senses. You've seen one aspect in... our coven. Gifts are rare - one in fifty, maybe - but everyone is different. There's a huge range of gifts out there, and some of them are more powerful than others."

―Riley

Jane's gift of tormenting illusion.

Most vampires find their key personality characteristics intensified by the vampire transformation in the same way their physical abilities are strengthened, but relatively few have abilities that can be classified as supernatural. More common would be a human with a love of learning becoming a vampire with an insatiable scholarly curiosity, or a human with a deep value for human life becoming a vampire with the strength to avoid human blood.
But a few vampires do develop additional abilities that go beyond the natural. These extra abilities are due to psychic gifts in the original human that are intensified in the resulting vampire. For example, a human who was very sensitive to other people's moods might develop the vampire ability to read thoughts or influence emotions. A human who had some limited precognition might develop into a vampire with a strong ability to see the future. A human with a good instinct for hunting might become a powerful vampire tracker. If a human already possessed a certain supernatural gift, this talent will be amplified many times after he is transformed into a vampire.
The proportion of supernaturally talented vampires to "normal" vampires is greater than the proportion of psychically gifted humans to "normal" humans. This is due to the same factor of temperament that results in more beautiful humans being selected to become vampires. Vampires are also drawn to gifted humans when they look to create companions. Some vampires actively seek out the gifted in the hope of utilizing that extra ability in their coven.
According to Eleazar, most vampire gifts are manifested in the mind, though there are certain exceptions. Benjamin was the best case - his power over the elements of nature is completely physical.
No gift ever works in the exact same way in two vampires, because no person (human or vampire) is ever exactly the same.