New Defender's Study Bible Notes
18:15 another disciple. That other disciple, undoubtedly, was John himself, who seems to have preferred never to identify himself by name in his gospel. The fact that he was known to the high priest suggests that he was known to the various other members of the Jewish council, probably including Joseph and Nicodemus. One can at least surmise that he may have been instrumental in their conversion to faith in Christ. John may well have been with Jesus when Nicodemus first “came to Jesus by night” (John 3:2), and thus was able to record that notable conversation (John 3:1-21).
18:15 with Jesus. It is noteworthy that, at this point John was still “with Jesus,” while Peter elected to be “with them” outside (John 18:18)—that is, with the servants of the high priest.