John gave more details that the other Gospels. To start with he told that Peter cut off the ear of the high priest's servant at the beginning of ch18. Since the high priest and apparently his servants (one let him in) knew John, wouldn't they know John was a follower of Christ? Thus, wouldn't it seem obvious to them that Peter, who was with John, was a follower of Christ. Last one of the servants spoke up who saw Peter during the arrest and admitted such. Was Peter in complete denial of reality, that they knew he followed Christ? Or, did Peter know and disown following Christ?
15 Simon Peter followed Jesus, and so did another disciple. Since that disciple was known to the high priest, he entered with Jesus into the courtyard of the high priest, 16 but Peter stood outside at the door. So the other disciple, who was known to the high priest, went out and spoke to the servant girl who kept watch at the door, and brought Peter in. 17 The servant girl at the door said to Peter, “You also are not one of this man’s disciples, are you?” He said, “I am not.” 18 Now the servants and officers had made a charcoal fire, because it was cold, and they were standing and warming themselves. Peter also was with them, standing and warming himself. (John 18:15–18, ESV)
25 Now Simon Peter was standing and warming himself. So they said to him, “You also are not one of his disciples, are you?” He denied it and said, “I am not.” 26 One of the servants of the high priest, a relative of the man whose ear Peter had cut off, asked, “Did I not see you in the garden with him?” 27 Peter again denied it, and at once a rooster crowed. (John 18:25–27, ESV)