Who is Dr. Parker from Wintergirls and what is their importance?

Dr. Parker is Lia's psychiatrist. Ever since Lia was assigned to Dr. Parker's study, Lia has refused to speak openly about her emotions and insecurities. Dr. Parker has patiently waited for Lia to open up, and when she does, Dr. Parker suggests that Lia be sent to the psychiatric ward of the hospital, which causes Lia to spiral out of control.