- "That's it... I'm sorry, but... I'm done..."
- —Kathleen asking to stop the experiment
Kathleen is only known as a "card tester" for the DPA. It is presumed she is an agent of some kind, though no specifics are given.
Kathleen's only role is to help in an experiment, testing Aiden's skills and, subsequently, Jodie's control over him. Initially, he is only used to check which cards she holds, but is eventually given free reign to do things on a larger scale. However, after the destruction of the room begins to increase in intensity, Kathleen becomes frightened and wishes to discontinue the experiment.
Aiden, now uncontrollable, pushes farther and farther until attempting to kill Kathleen, closing her airways and choking her (if not stopped by Jodie). When Cole and Nathan forcibly stop the experiment, Kathleen slides to the floor in tears. She is never seen again.
- Kathleen is the first character that Aiden frightens (in chapter play order).
- Kathleen is the first character that can be strangled by Aiden (in chapter play order).