Sarah used to be a medic in the Alliance Army and has saved countless lives. For this she was nicknamed the Guardian Angel.
During the time of the elemental war, she came to realize the harsh reality of war.
With the onslaught of a biochemical infection caused by a certain "corporation", she saw that merely saving lives wasn't enough. The war has to end and to do that, she will need to be more than just a medic.
With her elite skills, she has been given a chance to fulfill her potential by joining the Sacred Vanguards. Using advanced technology, she mastered the use of area-of-effect-healing equipment and middle-far ranged ionic weapons. Missions with her on board is a whooping 80% success rate with 0% mortality.
Now, Sarah has become an integral part of what the Vanguards stands for.