This is about Bret Stiles, but I'm actually not accusing him, I'm exonerating him. And what I'm about to say may sound farcical, but I'm serious. This is my first time submitting a theory here, and I hope this does not go against me as a theorist for not being substantial. But... 

Bret Styles cannot be Red John, because the visualize symbol is a variation on the CBS logo -- Network that airs The Mentalist. I'm quite serious about this. Although I don't want to stretch my theory too thin and speculate about the significance of the similar designs, I think the similarity is intentional, not coincidental. 

Before I submit another theory or theories accusing other people, I want to say that Bret Stiles is the most fitting suspect for several reasons that have already been mentioned by others in this forum, and the fact that he is the most fitting subject DOES NOT make him a red herring. But I still don't think it is him. 

I do, however, think visualize has some involvement or influence in the turns of events concerning RJ, because, for instance, Stiles has too much knowledge about things Red John, he's too powerful, and there are too many connections like the murders committed in the basement of that house years before RJ's murders became public. For that matter, Haffner, a member of Visualize is dirty, for certain -- but not necessarily RJ or one of his disciples. 

The list of 7 could very well involve people who are all in this together somehow, including RJ whom I believe is an individual, not a team. We know that Bertram and Kirkland have had private conversations regarding Jane and Red John; we also know of the trio in Bertram's office in episode 6.2. I think there is another trio that will be revealed very shortly: Stiles, Haffner, and Partridge. We will learn about the connections in the fourth episode this season. Note, that this consideration on groupings involves all 7 in one way or another, although the trio I suggest has yet to be materialized.

Some of the people on this list are blood relatives, or else one of them has a brother who has been affected by the RJ killings. I say this because there is a sibling issue with RJ's MO. On more than one occasion we know of a girl or woman whom he killed or had killed whose sister was spared. The basis for my suggesting there is an important  fraternal relationship in the Red John ring is based on this motif and on another relevant motif "Tyger Tyger." 

There are also two Brets -- but not really. One is a Bret the other is Brett. Brett Partridge is one of the Tygers; Brett Styles is not -- IMO. But if we wanted to get involved in anagrams and alliteration and what not, there's lots to play with with the T's in these names. Then again, these sound games are insubstantial -- maybe... maybe not. Show titles often indicate significant, clueful plays on words, and most of RJ's alias's are plays on the pseudonym "Red John." so it's not out of the question for Heller and other writers to use these devices.