Most likely,Red John is a person Patrick Jane knows but is not aware of his dark side.It is probably an important person who can watch what Patrick and the CBI team are up to at any time.His IQ is very high,as he can manipulate people and make them do anything to please his desire.It is possible that Red John is a member of the team or a person who closely works with the team because of his apparently perfect knowledge about Patrick and CBI movements,as he is always one step forward.I cannot name a person but it is probably and important one in the show. I chose Gale Bertram just because i had to in order to post my theory.