Oecumenius

"And those two," he says, "were cast alive into the lake of fire, and the rest were slain by the sword." O excess of justice! He did not deem the authors of the war and those co-responsible worthy of the same punishment; but the two, namely the Devil and the Antichrist, were condemned to fire, in which they will live forever, for this is hinted by their being cast alive into the fire; the rest were slain by the sword. By far it is preferable to give judgment by the sword briefly than by fire.

Commentary on Revelation ↗

Irenaeus

Inasmuch, then, as in this world some persons betake themselves to the light, and by faith unite themselves with God, but others shun the light, and separate themselves from God, the Word of God comes preparing a fit habitation for both. For those indeed who are in the light, that they may derive enjoyment from it, and from the good things contained in it; but for those in darkness, that they may partake in its calamities. …

Against Heresies Book V ↗

Bede

The two were thrown alive into the lake of fire burning with sulfur, etc. This seems to indicate that the devil and the Antichrist will be punished with a greater penalty than other humans or demons, as it is much more severe to be burned alive in sulfurous flames than to be quickly killed by the blow of a sword. Unless it signifies the divine retribution already being preempted against them. For he who does not believe is already judged (John 3). …

Commentary on Revelation ↗