Dark Angel (Night World Series)

The series takes place in a world similar to our own but one where vampires, witches, werewolves and shape-shifters live among humans without their knowledge. These supernatural races make up a secret society known as the Night World, which enforces two fundamental laws to prevent discovery: 1) Never allow humans to gain knowledge of the Night World's existence and, 2) Never fall in love with one of them. In Dark Angel, Gilian is saved from drowning by her guardian angel. Only visible to Gilian, Angel will fulfill her heart’s every desire. But when Angel starts making strange and sinister requests, Gilian must question who he truly is and where he came from.