What does John 18:16 mean?
John commonly refers to himself in the third person (John 1:35; 13:23–25; 18:15). It's possible that his mother (Matthew 20:20) was Salome (Mark 15:40; 16:1; John 19:25) and the sister of Jesus' mother Mary. Mary was related to the family of priests (Luke 1:13, 36). It's possible that John is an extended relative of the high priest, and known well enough that the gatekeeper let him come into the courtyard.The phrasing of this verse suggests Peter hesitated while John walked right through. Since they were both there to see what would happen to Jesus, it would make sense for John to go out and bring Peter into the outdoor courtyard.
What happens next is interesting, in that the servant girl questions Peter about his relationship to Jesus, but does not seem to do so with John (John 18:17). Scholars suggest Peter might have had a distinctive accent which suggested he was from Galilee (Matthew 26:73), making the gatekeeper suspicious. She was at least curious enough to ask. Peter's response will be heartbreaking and infamous.