Right - so out of the five that were on the couch, only 3 had the tattoo.. But how hard would it be for someone outside of the 'Tyger Tyger' group, to get the same tattoo, if they had inside man in the group, who knows what the secret tattoo is? This is what makes me think Bret.
Also, if Bret has nothing to hide, why was he so determined to avoid questionning from the FBI? I think Patrick is right and Stiles isn't actually ill - he just wants to disappear from the public eye or maybe Visualize? Maybe he has had enough of being some crazy cult leader?
Also, when Kristina Frye disappeared, it was Bret who knew where Jane could find her - he gave her the exact address.. I don't buy into all the psychic/inner eye stuff that Visualize is all about - even if it is a fictional story - it just doesn't seem right...

However, does anyone remember Walter Mashburn? The millionaire who let Patrick drive his Lamborghini and Patrick accidentally leaves the hand-brake off, causing the car to roll off the cliff? Well, he was in several episodes and always loved being a suspect.. We really don't know an awful lot about him and we haven't seen him in quite a while.. Just a thought..

To comment on someone else's theory though, I think the Tyger Tyger group are doing their own bidding, whilst 'trying' to catch Red John, but only putting in a small bit of effort, because they can in theory, pretend that some of the things they are doing were actually done my Red John? Passing the blame and reducing the amount of suspicion?