Before you choose a Character Style, read up on the idea and philosophy of creating a player character in the Atomic RPG System system. Refer to What Character to Play. Once you have a general idea about your character, you can determine the Character Style.
There are three basic Character Styles.
These three styles will round out your overall character idea and should really help you to bring your character into focus.
An Aggressor Style character is one who is primarily focused on attacking instead of defending. Aggressors are the ones that usually throw the first punch in a fight. Aggressors are focused on hurting or stopping their enemies, as opposed to watching over their allies.
A Neutral Style character will use skills, diplomacy, or non-damaging powers to attempt to resolve conflict, trying to avoid combat.
A Protector Style character is one that is primarily focused on defense of self or others. Protectors rarely throw the first punch in a fight. Protectors defend not only themselves but often focus on protecting and aiding those in need.