As it stands now, there are two active factions in the Necropolis. The first one is the F.C. Expeditionary Force, stationed in Camp Benjamin. The second, newer one, is the Abom Nation, comprised of several key abomination and freak NPCs in the Necropolis.
Only hideous freaks, abominations and zombies can get Abom Nation reputation points. Only normal humans and zombies can get FCEF points. (Zombies can earn both.)
Whenever you either download data from sensor clusters, or when you kill mobs in the necropolis, you get faction points for the appropriate faction. Either side gets positive points for killing necropolis zombies, necropolis spectres, or junkers.
Here's where it gets tricky. The freak and abomination npcs have slightly different faction point awards.
If you are human or zombie, you get positive faction points for killing any npc abom or freak.
If you're a freak or abomination, you get positive points for killing normal abom or freak mobs. However, abom and freak players get NEGATIVE points for killing abom or freak npcs that are part of the extermination contract given out at camp benjamin.
For more information or clarification, please contact Necanthrope.
Have fun!