The wolves themselves vary in physical appearance, just like their human counterparts. For example, the wolf that scares Laurent away from Bella (NM10) is described as: “It was enormous—as tall as a horse, but thicker, much more muscular. The long muzzle grimaced, revealing a line of dagger-like incisors. A grisly snarl rolled out from between the teeth, rumbling across the clearing like a prolonged crack of thunder.” So huge that Bella even mistakes it for a “bear” at first.
The other wolves are described: “One was a deep gray, the other brown, neither one quite as tall as the first.” And finally a “rusty brown monster” (NM10).
It is this “reddish brown” wolf that Bella focuses on, explaining “The wolf’s eyes were dark, nearly black. It gazed at me for a fraction of a second, the deep eyes seeming too intelligent for a wild animal. As it stared at me, I suddenly thought of Jacob,” (NM10) but it is not until her later dream that Bella realises that these eyes are actually “The black-brown, familiar eyes of Jacob Black.” (NM12)
The colour of the wolves seems to be randomly allocated. Jake’s reddish-brown colour could be connected with his skin tone, but if that were true then the others would also be a similar colour as they are of fairly similar human appearance. However, as wolves they are markedly different in appearance, although similar in strength and size.
In ‘Eclipse’ we discover that there are some correlations between human and werewolf form. Bella asks why Jacob is furrier than the others: “Because my hair is longer” (EC22)
The sheer “monstrous size” of these things are emphasised again and again. This links clearly with the actual changes in the boys as well, which Bella notes, although she doesn’t connect the two together until later. “These were just four really big half-naked boys” (NM14) As a human Jacob is “six five” (NM5) and she also remarks of the changes in Quil: “He looked bigger than the last time I’d seen him. What was with these Quileute boys? Were they feeding them experimental growth hormones?” (NM11) It seems that a period of rapid growth happens in the human boy before he becomes a wolf.
It is also noticeable that the human boy changes significantly in areas other than height when they have become of an age to turn into a werewolf. Jacob crops his hair short, just like Sam and the others, but “The planes of his face seemed to have hardened subtly, tightened…aged. His neck and his shoulders were different, too, thicker somehow. His hands, where they gripped the window frame, looked enormous, with the tendons and veins more prominent under the russet skin.” (NM11) Becoming a wolf is a sign of maturity, and he visibly ages as a human as well. This also seems to be true of Sam Uley, as his first description is: “closer to a man than a boy, and his voice was very deep.” (TW6)
The boys become very similar in their physical human appearance until they could be mistaken for “quadruplets” (NM14) as there was “something about the way they moved almost in synchronization to stand across the road from us, the way they all had the same long, round muscles under the same red-brown skin, the same cropped black hair, and the way their expressions altered at exactly the same moment.” (NM14)