Hunnigan is an operator at FOS (Field Operations Support), an organization which supports U.S. Agents in the field, and she has known Leon for nine years. She first got to know of Leon during the incident in which the President's daughter was kidnapped. She has displayed exemplary service assisting Leon from behind the scenes ever since that incident. While having no doubt suffered extreme shock following the sudden death of President Benford during the bioterrorist attack at Tall Oaks, she was still able to maintain a level head and use excellent judgment in assisting Leon and Helena in their escape, making use of her high-level IT and hacking knowledge to remotely unlock the security doors inside the university. As a highly respected and trusted member of the team, her superiors will often turn a blind eye during emergencies which occasionally allows her to exceed her authority. She will defiantly follow her own instincts in the face of danger, as can be seen when she furnishes Leon with confidential internal intelligence even though he is considered a suspect.
During RE4, Hunnigan assists Leon remotely. Although the two are cut off towards the middle of the game due to the actions of Saddler and Salazar, she reappears when the connection is restored just before the very end. For some reason she has removed her glasses at this point, and Leon jokingly hits on her, asking for her number. Hunnigan, who makes a point about keeping her professional and private lives separate, curtly refuses.