I think the key to the Red John mystery was revealed in this episode. Kirkland mentions how both he and his twin brother were abused by his father. Jane remarks that Bob must have been the stronger of the two. If Bob was stronger than Michael I could only imagine how psychologically damaged he is. Bob says that his brother grew distant from him as he found someone, who he thinks was Red John, who understood him. I think that the person that he actually met was Brett Stiles and the Visualize cult. Visualize would require someone to distance themselves from their families. The visualize group would show the kind of love to a deeply damaged young man who was abused by his alcoholic mother. It also goes along with the clue that Red John's first kills were on the farm owned by Visualize.
If that theory doesn't hold true, the next best guess I have is that Red John is not one singular person but rather a network of people. This network is more than likely the "tiger, tiger" group. This would explain why so many people suspected of being or knowing something about Red John always drops the "tiger tiger" line when they die. If the organization covers things up for other members and is full of corrupt law enforcement officials then it would make sense as to why there are so many different suspects throughout the series and why no real headway has ever been made in the case. If this proves to be true I think that in the reveal episode this truth would be revealed and the member of the "tiger, tiger" club is the one who killed Jane's family, and then the rest if the series will be dedicated to exposing the rest of these members.
