Who is Sister Katherine from Invisible Monsters and what is their importance?

Sister Katherine is one of the nurses at the hospital who takes care of Shannon. Sister Katherine is convinced that Shannon needs love to get her through the tragedy of losing her lower jaw. After Manus breaks up with Shannon, Sister Katherine begins scouring the hospital for men who have also suffered catastrophic facial wounds who could fall in love with a woman who looks like Shannon looks now. Shannon finds Sister Katherine's actions humorous, but has no intention of meeting any of the men of whom Sister Katherine tells her. Shannon does not believe that love will heal what ails her.