Who is Denon from Dead Witch Walking and what is their importance?

Denon is Ivy and Rachel's boss. When Rachel announces that she is quitting, Denon is very happy about the news and tells her that he's been trying to get her to quit for two years. He also tells her that he has sabotaged all of her assignments, hoping to make her appear incompetent. Denon puts a hit out on Rachel when he discovers that she is leaving with Ivy.