"Black Soul' (Titan #4) by TJ. Brearton

This is the last in this series and I have to say that I did not find it enjoyable. The main character is William, a man with a perpetual temper tantrum. His partner is his on and off love, interfering with his concentration on the business at hand. He goes from one personal struggle to another helped by his faithful partner, up to a point. Memories of past failures haunt him.