I have read all the accusations on Brett Partridge and agree completely. At least, that is what is evident with all these clues in the series so far. I would like to add that Bret Partridge always makes his appearance when there is a fake Red John at play (he has been in both of those episodes). Probably to look for the clues and find the imitators.
P.S. Only thing that bothers me is that he has not yet been shown as a "relentless manipulator" as quoted by Lorelei.