Don't use Vigilante ID's because Law Enforcement services in real life tend to not like them. Thus, not making sense for your role play. I'd recommend using the Civilian ID, but I don't think you are allowed to attack others, so scratch that idea. I'd stay with the Freelancer ID. Mercenary ID doesn't fit either. Freelancers are those whose morals show them the way to go. Mercenaries are only in it for the money.
