Like all servitors, he wears a black turtleneck. His eyes have changed from a clear grey during the combat with Molly Carpenter to a deep purple like a "bruised corpse" during the visit with the Grey Ghost. In Bombshells he is described as a pale skinned, fit man of middle height with dark, intelligent eyes and a military short haircut.
Listen is able to remain cool and observant in the midst of combat. He figured out Molly's illusions and was smart enough to wait out Harry Dresden's fire spell until it wore out. When dealing with the Grey Ghost, Listen could disarm her by displaying his humility and loyalty to his Lord. He has the protection of the Fomor Empress, as the Fomor Lord in "Bombshells" points out (when discussing Listen) that he would not be so stupid as to kill a "special pet of the Empress" even in an "accident".
In the seriesEdit
Listen is the emissary sent by to check on the Grey Ghost's progress in acquiring a body. Lady Shade sent a message back through him that she is confident she will acquire the body and be ready to move against the Ragged Lady and her her allies and to enter the fortress the next evening. It was observing this interchange that Harry Dresden realized that he was really dealing with Corpsetaker.