Jake Guffie is a human man. He first appeared in the novel Blood Rites.
Guffie worked as a porn actor, with the stage name Jack Rockhardt.
In Blood Rites, Harry enlists his help setting up a ward around the studio to block the Entropy Curse. Jake assumes Harry is doing some kind of feng shui and gladly helps. While doing so, lets it slip that Arturo Genosa is in love again whidh give Harry a break in the case. 
After Blood Rites he quit acting. Instead, he planned to start up a feng shui consulting business together with Bobby. He was the father of Emma's children, and took over custody of them after she died.