Obsidian Butterfly (Anita Blake: Vampire Hunter #9) by Laurell K. Hamilton
In this book, Anita travels to New Mexico in to help Edward, aka Ted Forrester, investigate a series of supernatural attacks. To Anita's shock, she discovers that "Ted" has a fiancee, Donna, who is a new age bookstore owner. Donna does not know Edward is an assassin; she becomes a target by trying to stop an unauthorized (but profitable) archaeological dig. Before this is resolved, Donna's children are kidnapped and abused.
Anita acquires a new power from the vampire Obsidian Butterfly, the first instance of her picking up a power from a vampire. She is nearly killed by another vampire; her "closing" of the marks with Jean-Claude and Richard has weakened her abilities, making her more vulnerable to metaphysical attacks. By the end of the book Anita is convinced that she needs to return to her relationships with Jean-Claude and Richard.
As with previous novels, "Obsidian Butterfly" refers to a location within the novel itself - a nightclub operated by Itzpapalotl, a vampire who claims to be the Aztec goddess of the same name. "Obsidian Butterfly" is one of the English translations of Itzpapalotl.
This is the first book in the Anita Blake series to be originally released in hardcover. From this point on, all the books were first printed in hardcover, then later released in paperback. You realize books are becoming popular when first editions are hardcover.