Ghouls as slaves or workes for those Raiders/Mercenaries to do jobs in highly radiated areas.
Or raiders/mercenaries as guns for hire for those ghouls, prewar citizens who knew where was hidden lot of cash, gear, medicine, etc. Now they use their knowledge to obtain those things in large numbers to hire bandits, the only way to stay alive in harsh wasteland on your own when you are not best marksman.
Or they were rich faggots, who didnt get in time in Vaults, now they pay skilled scums to became their bodyguards.