Throughout the franchise, each character belongs to their own kind of faction depending on their fate in the game. Generally, Light is the 'good' side while Dark is the 'evil' side.
These are regular human beings who go on living their life per usual despite strange things they may have encountered. They are most strongly represented by the Deputy Sheriffs or even military forces, they are represented in Alan Wake as the Bright Falls Sheriff Station
People in the "Light" faction are those who are strong with using "Light", when light is their protection. The only people who belong in this faction are:
People in the "Dark" faction are those who are strong with using "Dark", where the darkness is their greatest weapon. The only people who belong in this faction are:
Those in the "Taken" faction are people who have been absolved by the dark presence and have turned into Taken, whom of which only go about to kill whoever they may come into contact with. These people are mere shells filled with darkness and cannot be restored to their human selves once turned.