Albert Barnes Commentary John 18:15-18

"And Simon Peter followed Jesus, and [so did] another disciple. Now that disciple was known unto the high priest, and entered in with Jesus into the court of the high priest; but Peter was standing at the door without. So the other disciple, who was known unto the high priest, went out and spake unto her that kept the door, and brought in Peter. The maid therefore that kept the door saith unto Peter, Art thou also [one] of this man`s disciples? He saith, I am not. Now the servants and the officers were standing [there], having made a fire of coals; for it was cold; and they were warming themselves: and Peter also was with them, standing and warming himself." — John 18:15-18 (ASV)

Another disciple. Probably John. Some critics, however, have supposed that this disciple was one who lived in Jerusalem and, not being a Galilean, could enter the palace without suspicion. John, however, mentions that he was known to them to show why he was not questioned as Peter was.

It is not probable that any danger resulted from it being known that he was a follower of Jesus, or that any harm was planned against them for this. The questions asked Peter were not asked by those in authority, and his apprehensions which led to his denial were groundless.