So I made my own enemies which are a custom NCR trooper. And I need them to be hostile towards the player and any other faction and allies with each other. I managed to make it so that killing them won't result in infamy. I tried setting them to the Fiend faction, so they would be hostile, but they won't attack me. So if anyone could tell me what faction to set them for or I could make my own custom faction.

Thanks in advance.