"He must know to pay attention to a given shadow or it all blends together in the background, and certain locations (such as the Carpenter Household or an awakened Demonreach) are beyond his reach, and this ability can be blocked by certain powerful beings such as Mab, the Queen of Air and Darkness.At a book signing in Houston, Butcher claimed that in writing Nicodemus, he simply created someone that would be "the flipside of Michael Carpenter."