The D&D alignment system was much more ridged in earlier editions. Firstly it accepted (as do many legal codes) a moral distinction between killing in battle or for self defence, and murder. And secondly it made neutrality the norm. An ordinary decent person who never hurts anyone would be neutral. In order to qualify as good, it was necessary to be actively altruistic - i.e. seeking the benefit of others without reward for yourself. It would be difficult for a mercenary to be "good" under those definitions, since no matter how heroic your actions are the instant payment is accepted it is considered neutral.idk mercenaries kill people for money, why are they allowed to be neutral or even good? assassins are just mercenaries who work on very specific targets. it's that whole "backstabbing people to death is EVIL just THE WORST" attitude that made them evil, but I don't want to get into an argument over alignment, I'll be up all night.