Deadshot was born Floyd Lawton, the son of Genvieve and George Lawton, brother to Edward. The Lawton's were an 'old money' family, and the children wanted for nothing. Nothing except the love of their parents, that is, who were always too busy hating each other to show their children any kind of parental affection.
Neither Genvieve nor George could remember the cause of the schism between them, though to be perfectly honest neither really cared either. They were to involved in their petty struggle with each other to waste time worrying about the cause.
Things came to a head when Floyd was in his teen years. His mother attempted to manipulate Floyd into murdering his father, thinking that her unruly second son would be easy putty to mould, however he proved indifferent to his parents squabbles, and refused to become involved. Unfortunately Edward overheard his mothers false entreaties, and took it upon himself to put an end to his father's excesses. He took his fathers hunting rifle, and made a vow to kill the old man.
Floyd found out about his brothers plan, and went to stop him, not for any love he felt for his father, but because he didn't want Edward to throw his life away because of his mothers trickery. He confronted Edward just as he cornered George in the families conservatory, and tried to wrest the rifle from his brother. The scuffle turned chaotic though, and in the confusion bullets were fired. In the aftermath George was left paralyzed and Edward was killed.
Despite the horrific and sadly avoidable nature of the death, the Lawton's dealt with it in house, refusing the allow the police to interfere with their family's misadventures. Floyd, disgusted with his parents and himself, left the family home, and after a year of aimless wandering, joined the United States Army Rangers. Despite normally lacking a true respect for authority and anything resembling a real patriotic drive, Lawton thrived in the military, if only because he was still in a kind of PTSD fugue state, and gave himself over entirely to his training, like an automatron with no other functions.
In his short time with the Rangers he was confirmed with over one hundred and fifty kills, a remarkable feat, though some armchair generals argued that he took unnecessary, and quite often suicidal risks, to reach this figure. In fact even his own partner and spotter, Paul Dennis, complained that Lawton was reckless to the point that he suspected he was trying to get himself killed. Regardless of all this, Lawton's results spoke for themselves, and eventually somebody he was noticed by people in high places.
He was head hunted for by the CIA, who decided he was the perfect agent to take on wet work. All of his work with the agency is completely confidential, though he claims he is directly responsible for the collapse of a banana republic government, and for a while singlehandedly stemmed the tide of the Latverian Unions steady march towards total power in Europe. Though both these claims are highly suspect, it is true that he was an extremely effective agent.
He 'left' the Agency though, ostensibly complaining that he could no longer stomach other men forcing their ideologies down his throat, and took up freelance mercenary work, working for just about anyone who could foot the bill. Eventually this attracted the attention of ARGUS, and he found himself on the wrong end up a massive sting operation. He was remanded into the custody of Amanda Waller, standing out as a clear candidate for Task Force X membership, where he has remained to this day.