Alignment is a system designed to limit same-faction killing sprees. At the very beginning of darkfall game, you are given enough alignment to kill one member of your own guide. But you will turn red if you kill one more. Being red makes you become a target anyone can hit without getting penalties.
You will not turn grey or get any alignment penalties for killing your own faction members.
Three ways are available for you to build up your alignment, kill players of enemy factions, kill red players, or complete quests.
Players in darkfall tend to use all sorts of tricks to keep away from alignment system. They will jump into your swings when you are attacking something else. They will invite you to a group without giving you any notices. Watch closely about your surroundings.