What does John 18:13 mean?

A common scholarly assumption is that whatever business was conducted in the temple was supervised by the family of the high priest. Jesus, on at least one occasion, had greatly disrupted that commerce (Matthew 21:12–17). It's possible Annas and Caiaphas had a personal bitterness towards Jesus, beyond questions of status and reputation (John 11:48–50; 12:42–43).

According to the Old Testament, high priests were supposed to serve for life (Numbers 35:25). Roman politics preferred to avoid giving locals that much influence, and so they "appointed" their own choice to that title. Annas was the approved high priest until about AD 18, replaced by his son-in-law, Caiaphas. As noted in the following verse (John 18:14), this is the same Caiaphas who accidentally summarized Jesus' role as Savior (John 11:50).

John typically refers to himself in third person (John 1:35; 13:23–25). In the passage which follows, it's likely that John is the unnamed person who goes with Peter (John 18:15–16). Since that person is said to be "known to the high priest," it would suggest John had some interaction with the family of Annas and Caiaphas.