Ambrose of Milan

And by this time there was a fire burning in the house of the High Priest; as it follows, And when they had kindled a fire, &c. Peter came to warm himself, because his Lord being taken prisoner, the heart of his soul had been chilled in him.

Catena Aurea by Aquinas ↗

Bede

And when they kindled a fire in the midst of the courtyard and sat around it, Peter was in their midst. There is a fire of love, and there is also a fire of desire. Of this, it is said: "I came to cast fire on the earth, and what will I, if it be already kindled?" (Luke 12:49). Of that: "Behold, all you that kindle a fire, that gird yourselves with flames: walk in the light of your fire, and in the flames that you have kindled" (Isaiah 50:11). …

On the Gospel of Luke ↗

Bonaventure

And therefore he adds: Now when a fire had been kindled in the middle of the courtyard and they were sitting around it, Peter was in their midst: in which is shown the tepidity of love and of the interior fire. Whence the Gloss: "What the malignant assembly was carrying on inside the house of the high priest, the fire kindled outside amid the cold of the night was figuratively demonstrating. …

Commentary on Luke, Chapter 22 ↗