Jesus tells them the time has come. This is the last wine he will drink until the kingdom of God arrives.
He tells Peter that Peter will deny knowing him 3 times before morning. Peter is aghast.
He takes the disciples to the garden of Gethsemane. Peter, John, and James fall asleep while Jesus prays. Judas arrives with the authorities carrying swords and clubs. All the disciples flee, except for one:
"A young man was following Him, wearing nothing but a linen sheet over his naked body; and they seized him. But he pulled free of the linen sheet and escaped naked."
As we noted above, this sounds reminiscent of the young man of Secret Mark, and of the Beloved Disciple, the author of the gospel of John, whether that is the Apostle John, or the disciple Lazarus, or someone else. The writer of the gospel of John had details about Jesus's prayers in Gethsemane as well as the arrest and subsequent events that none of the other gospels include.