Background & Early Life
Not much is known about Andrea's background or early life except that she is a survivor of the Cordyceps Brain Infection outbreak. She is a member of the Fireflies who worked as a sniper lookout at the University of Eastern Colorado alongside Marc.
Events of The Last of Us
Marc and Andrea are both members of the Fireflies who managed a sniper's nest at the University of Eastern Colorado. Together, they recorded anything and anyone who entered the premise of the University. According to their log, they seemed to have a friendly relationship—with Andrea "snagging" apples to share with Marc and Marc wishing Andrea a Happy Halloween.
On November 5, Andrea fell asleep while managing the sniper's nest, and Roger, another member of the Fireflies, yelled at her for sleeping. In turn, Andrea called him a "prick" in her log, implying that the two do not have a good relationship.