19 In the line of Matthew's narrative we come next upon this statement: “And they that laid hold on Jesus led Him away to Caiaphas the high priest, where the scribes and the elders were assembled.” We learn, however, from John that He was conducted first to Annas, the father-in-law of Caiaphas. On the other hand, Mark and Luke omit all mention of the name of the high priest. Moreover [we find that] He was led away bound. For, as John informs us, there were at hand there, in the multitude, a tribune and a cohort, and the servants of the Jews. Then in Matthew we have these words: “But Peter followed Him afar off unto the high priest's palace, and went in and sat with the servants to see the end.” To this passage in the narrative Mark makes this addition: “And he warmed himself at the fire.” Luke also makes a statement which amounts to the same, thus: “Peter followed afar off: and when they had kindled a fire in the midst of the hall, and were sat down together, Peter sat down among them.” And John proceeds in these terms: “And Simon Peter followed Jesus, and so did another disciple.
That disciple (namely, that other) was known unto the high priest, and went in (as John also tells us) with Jesus into the palace of the high priest. But Peter (as the same John adds) stood at the door without. Then went out that other disciple, which was known unto the high priest, and spoke unto her that kept the door, and brought in Peter.” For the last fact we are thus indebted to John's narrative. And in this way we see how it came about that Peter also got inside, and was within the hall, as the other evangelists mention.
Source: The Harmony of the Gospels (New Advent)