The Reapers

The reapers are a group of ex policemen that wander the land. Prior to the apocalypse, they were swat, specializing at riot control and dispersing groups. Now, after the apocalypse, they use their expertise to kill leechers. 
Generally, they find it easier to offer services to groups they encounter and collect rewards such as supplies, than too look for supplies themselves. They do search though when there is need. They are ruthless, uncaring but honorable. They will never harm someone if they don't have a reason to, but they may leave someone to be devoured by leechers if he won't give them what he promised. They won't hesitate to take supplies from groups with children, knowing they may starve to death, if they have offered services before. 
Aside from protection, another service they provide is information. They often give information about other groups nearby, but at a cost. The cost is not always supplies, as they often have enough of it. usually, they seek to have sexual intercourse with some of the groups' women, in exchange for protection against leechers.