I'm thinking more and more of this Ron being Red John...always around (in important episodes) without talking much, and corresponding to the portrait and clues we have (no?). He meets Bertram at the hospital (6'39') where he can go as he is not suspected. He knows the troubles the discovery of the Blake association made and can walk freely during this time, as nobody knows he is part of the association, not even Bertram and Smith.

Bertram and Smith are n°1 suspects by the CBI so Bertram escapes because under the name of the organization, he took part into reprehensible acts. But he is not Red John, nor Smith is.

So I think Ron is part of Blake association which is a great cover as it counts many members. Bertram and Smith don't know he is part of it.

He can also be Bob kirkland's brother.

 What do you think ?