The psychopathic stare also referred to as the reptillian gaze is common with HPD's and other Cluster B personality disordered individuals.
http://www.stargods.org/ReptilianStare.htm
Anthony Hopkins does it very well as Dr. Hannibal Lecter in the movie The Silence of the Lambs.
Mostly he does this while confined in his tiny cell with its glass casing as he gazes out at Agent Starling played by Jodie Foster.
The secondary affect this gaze has with HPD's is most times it makes their current unwitting victim feel really special. However done too much it naturally creeps a normal person out. The HPD being a partial psychopath (really partial sociopath as sociopaths are the non violent manipulative version of psychopaths) also known as Anti Social Personality Disorder mimics many of the actions of normal people to try to fit in during situations but its hard to always be on playing a role all the time and that would explain why they slip up sometimes and stare too often and too long. They don't know whats appropriate because they are not normal their mind is disordered so naturally they don't know how to act normal despite all of their practice to accomplish the illusion of normality.
Also about her meanness...
