Objection 1. It would seem that there is no sorrow in the demons. For since sorrow and joy are opposites, they cannot be together in the same subject. But there is joy in the demons: for Augustine writing against the Maniches (De Gen. Contra Manich. ii, 17) says: "The devil has power over them who despise God's commandments, and he rejoices over this sinister power." Therefore there is no sorrow in the demons.
Objection 2. Further, sorrow is the cause of fear, for those things cause fear while they are future, which cause sorrow when they are present. But there is no fear in the demons, according to Job 41:24, "Who was made to fear no one." Therefore there is no grief in the demons.
Objection 3. Further, it is a good thing to be sorry for evil. But the demons can do no good action. Therefore they cannot be sorry, at least for the evil of sin; which applies to the worm of conscience.
On the contrary, The demon's sin is greater than man's sin. But man is punished with sorrow on account of the pleasure taken in sin, according to Apocalypse 18:7, "As much as she hath glorified herself, and lived in delicacies, so much torment and sorrow give ye to her." Consequently much more is the devil punished with the grief of sorrow, because he especially glorified himself.
I answer that, Fear, sorrow, joy, and the like, so far as they are passions, cannot exist in the demons; for thus they are proper to the sensitive appetite, which is a power in a corporeal organ. According, however, as they denote simple acts of the will, they can be in the demons. And it must be said that there is sorrow in them; because sorrow, as denoting a simple act of the will, is nothing else than the resistance of the will to what is, or to what is not. Now it is evident that the demons would wish many things not to be, which are, and others to be, which are not: for, out of envy, they would wish others to be damned, who are saved. Consequently, sorrow must be said to exist in them: and especially because it is of the very notion of punishment for it to be repugnant to the will. Moreover, they are deprived of happiness, which they desire naturally; and their wicked will is curbed in many respects.
Reply to Objection 1. Joy and sorrow about the same thing are opposites, but not about different things. Hence there is nothing to hinder a man from being sorry for one thing, and joyful for another; especially so far as sorrow and joy imply simple acts of the will; because, not merely in different things, but even in one and the same thing, there can be something that we will, and something that we will not.
Reply to Objection 2. As there is sorrow in the demons over present evil, so also there is fear of future evil. Now when it is said, "He was made to fear no one," this is to be understood of the fear of God which restrains from sin. For it is written elsewhere that "the devils believe and tremble" (James 2:19).
Reply to Objection 3. To be sorry for the evil of sin on account of the sin bears witness to the goodness of the will, to which the evil of sin is opposed. But to be sorry for the evil of punishment, for the evil of sin on account of the punishment, bears witness to the goodness of nature, to which the evil of punishment is opposed. Hence Augustine says (De Civ. Dei xix, 13), that "sorrow for good lost by punishment, is the witness to a good nature." Consequently, since the demon has a perverse and obstinate will, he is not sorry for the evil of sin.
Source: Summa Theologica (New Advent)