​From Wikipedia, the free encyclopedia.   Seth Peterson (born August 16, 1970) is an American actor, best known for his role as Robbie Hansen from 1999 until 2002 on the television series Providence. Peterson was born in The Bronx, New York, the son of Cheryl Peterson, a theatre founder and paralegal, and George Kanouse, a teacher. Peterson is currently playing the recurring role of Nathan Westen, the younger brother of the lead character, Michael Westen in Burn Notice (2007) on USA Network an ...