Alastor is cunning, manipulative and cold, but has a charming aura that attracts people like a magnet. He dislikes most touch from past traumas and experiences, but prefers not to talk about it.  Alastor  has always been awkward, a little sharper on the edges, more reserved, less likely to giggle and smile and play. He’s been like that from the start, hard to read unless you know him. His happiness and amusement is a quirk of the lips and  light teasing. 
He's the killer.