Peter stood with those who arrested Christ, warming himself at a fire. Perhaps someone threw on more coals, causing the flames to flare up, making Peter recognizable.
The question (v. 25) again expected a negative answer, making it easy for Peter to lie.
him whose ear Peter cut off (v. 26) — Malchus (John 18:10)
Question (v. 26) is straightforward
Peter’s third denial occurred as the rooster crowed — John 13:38. He denied with cursing and swearing (Matthew 26:74; Mark 14:71).
Peter did not deny who Jesus was, only that he was one of the disciples.
The Lord turned and looked at Peter (Luke 22:61) perhaps in accusation or in love — or both.
Most commentaries focus on what Peter did wrong. But perhaps the point is that we will fail but Christ won’t. The contrast in this passage is between Peter’s response to questions and Christ’s response to questions.It is not so much a focus on Peter but on the One who never fails.