Created as one of the principal characters of Brian Azzarello and Eduardo Risso's creator-owned series 100 Bullets, Agent Graves actually appeared prior to the first issue of the series in Vertigo: Winter's Edge #3 wherein a self-contained short story set in the 100 Bullets universe was told giving people an idea of what the series would be about and providing some mystery about Agent Graves. The character's motives and ties are left to be guessed at for much of the series and it isn't until the book begins to reach its climax that more detail is given and Graves becomes more of a defined man than a strange figure popping in and out random individual's lives.
Key Story Arcs
Agent Graves first appears as a mysterious man, giving people a picture, irrefutable evidence that the person in that picture greatly wronged them, a gun and one hundred untraceable bullets.
It is later revealed that Graves is the leader of the Minutemen, a group of enforcers who used to work for an organization known as the Trust. The Trust betrayed the Minutemen and supposedly killed them all. However, Graves survived and has been gathering the remaining members of his group as well as others to form a new group of Minutemen and take down The Trust.