The face in the middle who is being eaten by Lucifer and has his feet sticking out is Judas. It is a fitting punishment for him because he betrayed Jesus by telling the Romans where Jesus was, where he was then violently crucified. He also betrays God directly by doing this, which is essentially angering God. This would be the reason why the face is red. The face is representing the feelings God has towards this specific sinner. By putting Judas head first in, he will not be able to see where anyone and he will not be able to betray them the same way he betrayed