Jessica has always been emotionless since a child. People think she is cold, uncaring and tactless. Everyone thought it was her natural trait, until Dr Kim remarked Jessica had Alexithymia after a severe head collision when she was a child.

Alexithymia /ˌeɪlɛksəˈθaɪmiə/ is a personality construct characterized by the sub-clinical inability to identify and describe emotions in the self.The core characteristics of alexithymia are marked dysfunction in emotional awareness, social attachment, and interpersonal relating. Furthermore, individuals with alexithymia have difficulty in distinguishing and appreciating the emotions of others, which is thought to lead to unempathic and ineffective emotional responding. Alexithymia is prevalent in approximately 10% of the general population and is known to be comorbid with a number of psychiatric conditions.

—Wikipedia