She met Shooter when he rescued her from some pesky zombies, and she struck up a deal with him.
CK Zombies Edit
Evelyn plays a minor role in CK Zombies, only helping Shooter shoot stuff, airlifting supplies and getting supplies.
CK Zombies 2Edit
Evelyn's role was beefed up in the second game. A missile had hit her and her pilot's helicopter which caused it to explode. She was then sent to kill Zombies and then help out a doctor, named Blunt.