McCullough is shown to be laconic and serious. She does not tolerate the boorish and often sexist antics of her male co-workers. She sometimes seems to be one of the nicer guards and occasionally willing to help inmates.
Suffering from PTSD after serving in the military and experiencing the prison the riot, McCullough develops self-harming behavior and begins stubbing cigarettes out on her body.
In the final season she starts illegally selling phone chargers to inmates using Alex as her mule. During one of their hand offs she kisses Alex and they eventually start a relationship.