Galatians (prelude pt. 2) Rise of James a man out of nowhere and Peters decline in Jerusalem

This is further talk about the origins of James's influence - how he "suddenly appears" in a position of leadership in jerusalem with no backstory- almost like a "melchizidek" of the new testament but in my view in a negative sense. Also talk about the decline of Peter's influence in Jerusalem which led to his fearful vacillating in Antioch referred to by Paul in Galatians 2.