Susan is King’s second in command of ITS CLAWS. Her house is their base of operations in Vancouver. It’s not a great place to live, but it keeps them under the radar, or at least that’s what they thought.
Susan is also a spiritual person. Her beliefs included life after death and reincarnation. She’s not afraid to die, since, in her terms, there is no ‘death’. She also won’t turn away a stranger in time of need. Benjamin knocks on her door, and she lets him in.
In the whole scheme of the plot, she is the most likable female. And, because of her previous training, she knows how to work the controls at the CCC broadcasting studio. Because of her knowledge of technology, Benjamin gets to have one more sermon.
(She would be equivalent to Mary Magdalene.)