Richard Paladin is an assassin with the EPA.
Yes, that EPA which stands for the Environmental Protection Agency. When he first found out his prospective employer was the agency set up to fight pollution he was a tad surprised but that went away quickly because his recruiter made it sound almost plausible and, truth be told, Paladin did not really care that awfully much. He needed a job and he had no decent prospects.
It is interesting and rather telling about the whole EPA-assassin gig that he, recently out of the Army, learned of the opportunity from an ad in the back of a Hustler magazine. There are two noteworthy parts to this. First is that he did not think it strange that the EPA would be using Hustler to recruit. Second is that he never bought the issue he was reading but just 'studied' it at the newsstand.
Something else good to know is that Richard Paladin is not his real name. We do not learn his actual name, just the one that his new boss set him up with when he met the guy, got the job, and set up home in Falls Church, Virginia. From them on he would use a wide assortment of aliases as he traveled the country dispatching bad guys, tossing these other fake identities as soon as he was done with them to resume being his full-time fake identity.
A couple more important facts concerning Paladin need to be presented. First is that he is most definitely not a nice man. Most assassins would fit that description but Paladin does so especially well as evidenced by his comment early in the first adventure that "believe me, you haven't lived until you've emptied the magazine of a high-power handgun into some unsuspecting son of a bitch. It's an awesome feeling you get seeing that look of total surprise followed by a glimmering awareness that this is the moment of death."
Next is that he needed a job because he had just been kicked out of the Army. If it was explained why the military and he ended their relationship, I missed it but I can hazard the guess that Paladin did not play well with others. He is miffed a lot of the time and totally uncaring the rest of it. He has little good to say about the intelligence or integrity of anyone. To give him some credit, he does not consider himself particularly better than others; he just could not name any person who would deserve being respected.
That low opinion about people extends into his personal life. He has not close attachments and does not miss it at all. When he was in the army, having joined as soon as he could to get out of a dirt-poor life in North Carolina, he spent most of his time being a womanizer focusing on wives of officers who would prefer to spend their off time on the links. They wanted a diversion and he provided it, enjoying the physicality of it and nothing more.
But Paladin is not a total waste of oxygen. He might not have any great regard for his fellow man but he is not a psychopath enjoying killing. He does it because he is good at it and it pays the bills. Plus a bit more by rounding the expense reports up a tad. Or maybe just a bit more than a tad.