Red John is Patrick's Alter Ego. An evil and opposite part of Patrick. This is why RJ is always one step ahead of Patrick, he already knows where Patrick is headed.
I don't think Patrick is aware he exists though. Patrick is always sleeping on the couch because his alter ego was out and about in the night taking care of RJ business.
The RJ side has control of the suspects either directly or through manipulation but I don't think anyone has ever seen RJ in person. With an alter ego even the voice and accent will change.
The very symbol RJ uses is a self portrait only the way the hair flows is reversed, reflecting the opposite or mirror image of himself. Notice the slanting of the eyes just like Patrick's.
As far as when the woman said something about the two meeting the first time, that could easily have been deception.
