The man we are looking for is JASON COOPER, yes the guy who we have been told is weak (in the episode about Visualize where a guy wanted to take over this group). That was smart its like no one have had mentioned him in theories.

In my theory Stiles is just a puppet of Cooper just a face and that show was just for keeping us away from Cooper beacuse who would even consider a guy who fails on his mission (that wouldnt be so red johns).

In last episode he is fully back like nothing ever happend and lets be honest - producers have to choose someone who already appeared in some episodes not just one or two that would be stupid and make me feel like i wasted time watching this (imagine a situation where red john is being revealed and he is totally new person and only Jane is like OH ITS YOU I HAVE MET YOU WHEN I WAS 2..... stupid)

plus he is old enough and he lives in a shadows (behind the scenes he is the head of the visualize and just use stiles to show his power)

Just someone to think about is Tallman Bunting. Season 2 episode 21. Jane placed chess with him mentally. He has very high connections because he go off with all the charges, he's very wealthy. He is also like Jane in that he is very good with puzzles.

Red John is one of the visualize. He is a man (for sure), and he was in Alison farm, I think he started before the age of 30.

CBI agent Ray who is trying to get Agent Lisbon to join him in independant consulting.

I think Jane already knows who Red John is but does not have enough proof yet and does not want to scare him away and that everything to have happened up to now was just acting to get closer to him.  I think the scene where Van Pelt opens up to Stiles was staged and is just meant to tempt Red John to approach her. 

I think that maybe Red John is not a member of Visualize, but he wants Jane to believe he is (maybe he even wants to mislead Jane into going after Bret Stiles specifically, either because he would obviously make such a good suspect, or maybe because Red John has some personal issues with Stiles and Visualize that he cannot solve by simply killing them).

I think that we just don't know why yet. Maybe Visualize (or Stiles) has taken some relative of Red John long ago, maybe Red John believes that Visualize is the only organization with enough power to compete with him and he wants to use Jane and the CBI to take them down, maybe he even has strong religious beliefs and wants to destroy Visualize for religious reasons. Or maybe Bret Stiles knows too much about him and has become a threat, some kind of threat that would be too dangerous to simply kill (imagine if Stiles has left a note somewhere in a safe to be opened after his death, revealing the identity of Red John...)

I think maybe is FBI Agent Kirkland (Kevin Corrigan). He shakes hands with Jane, I don't remember in what episode, I think in season 5. Maybe in the flashback when Jane first arrives at CBI.