Erin Mason is a crisis manager hired by Catherine after the scandal broke.
After it was publicly revealed that Harper Avery had assaulted multiple women during his life, Catherine hired Erin to help them deal with the resulting scandal. Her first move was to find a medical charity with a high-profile case for Jackson to work on with Meredith. Her next planned move was to go after the women Harper Avery assaulted. When Catherine, Jackson, and Richard objected, she said someone has to go down for it. Catherine said it would have to be her, but Jackson didn't want his black mother to take the fall for his rich, white grandfather. Catherine said it wasn't his decision, so they made a plan to save face with Catherine taking the fall.
Erin helped Catherine prepare a statement, but before she could deliver it, Jackson and Meredith came in with a statement they'd prepared in which Catherine would announce dissolving the Harper Avery Foundation and creating the Catherine Fox Foundation to replace it. Jackson summarily fired and dismissed Erin.
She is a crisis manager.