Angel

Angel features heavily as the missing vampire in Night Air Syndrome who Pem & Friends are contacted to locate. He was made into a more monstrous and less human version of a vampire by a crystal embedded in his chest and is responsible for the disappearance and subsequent vampire-turning of several local children.

Physical Appearance
Angel appears in Night Air Syndrom as a monster "barely resembling a human". He is depicted on the cover of the novel as tall and skeletal, with no hair, pointed ears, and claws on both his hands and feet. He is described in the text as having wolflike jaws. There is a crystal, similar to that on Lila's necklace, embedded in a swath of scar tissue on his chest.

As a human, Pemberly thinks he looked a little older than Joel, and happy.

Night Air Syndrome
Pemberly and the other heroes are sent to Arizona at the outset of this novel to track down a vampire who's been reported missing by his vampire "family"....

Trivia

 * Angel was apparently a regular at the cowboy-themed bar where the quartet meet Hazel.