A.T. Robertson Commentary John 18:15

"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;" — John 18:15 (ASV)

Followed (ηκολουθε). Imperfect active of ακολουθεω, "was following," picturesque and vivid tense, with associative instrumental case τω Ιησου.

Another disciple (αλλος μαθητης). Correct text without article ο (genuine in verse 16). Peter's companion was the Beloved Disciple, the author of the book (John 21:24).

Was known unto the high priest (ην γνωστος τω αρχιερε). Verbal adjective from γινωσκω, to know (Acts 1:19) with dative case. How well known the word does not say, not necessarily a personal friend, well enough known for the portress to admit John. "The account of what happened to Peter might well seem to be told from the point of view of the servants' hall" (Sanday, Criticism of the Fourth Gospel, p. 101).

Entered in with Jesus (συνεισηλθεν τω Ιησου). Second aorist active indicative of the double compound συνεισερχομα, old verb, in N.T. here and 6:22. With associative instrumental case.

Into the court (εις την αυλην). It is not clear that this word ever means the palace itself instead of the courtyard (uncovered enclosure) as always in the papyri (very common). Clearly courtyard in Mr 14:66 (Matthew 26:69; Luke 22:55). Apparently Annas had rooms in the official residence of Caiaphas.