Satan and the rest of the demons are truly the most tragic beings in existence.
The reason I say this is because they are the most powerful deceivers to ever exist, deceiving themselves and being in an eternal state where, even though they feel they made the wrong choice, they are so prideful, so invested in their belief, that to acknowledge the truth is impossible.
Their choice is that of self-deification.
To explain that we need to go back.
In the original Scriptures, Satan appears as one of the Archangels, called Lucifer, the Bringer of Light, the Dawn, until his rebellion against God.
Most cultures display this act of rebellion as an act of attempted liberation. “God imposes His will on the world, but Lucifer refused to submit. He was therefore cast away by God and punished by Him to eternal damnation.”
The truth however is different; Lucifer, Satan, did not rebel against “God and his order”, but rather against his own nature, as a being created by God. His rebellion was an attempt to become like God, to become uncreated (aktistos), and to be a God himself.
This is impossible. It is impossible for a created thing (ktisto) to become uncreated (aktisto). There is no way to trascend the boundary — something finite cannot become infinite, something caused cannot become the Uncaused Cause, and this ontological limitation is the cause of the eternal damnation.
For Satan was not “arrested”, nor was he “locked away in hell as a prisoner”. He is a prisoner of his own self, tormented by his own delusion of grandeur. He refuses to acknowledge the ontological distinction, and is therefore eternally damned by himself. Where God is, he cannot be, because the truth is too much to bear. God is infinite, Satan is finite.
In this sense it is his ego that holds him a prisoner in his own hell, which is his own head. In truth it is extremely easy to “escape”. The only necessity is to acknowledge his own true nature; a being created by God. His pride and ego however, ensure that he is always a prisoner.
In this self-delusion of self-deification, we can see that Satan is not evil in the sense of him wanting to cause damage. He is evil because in his delusion, he is trying to convince other he is right; he believes that through worship and power he might finally achieve self-deification and reach the status of God; in his own head he might just become uncreated.
Hell therefore is not a place, nor a prison where “evil people go”, it is a state of the spirit, a lack of connection with the ontological source, which is God.
This is also why Satan, or any of his followers (ie creatures with their own egos and pride, convinced that they can achieve self-deification), retreat in the light of Truth; it is why when they whisper in your ear intrusive thoughts you can easily get rid of them by laughing at them, or by shooing them away like flies. If you treat them more than what they are, for example as powerful entities, you grant them power and influence over you.
The other causes of demons running away, prayer and forgiveness, are also in the same vein. Prayer works for the simple fact that you call upon the cause of their self-hatred and self-imposed hell for help. Forgiveness is their worst situation. Their ego and pride would never let them admit to themselves that they are wrong, as if they are wrong they must correct themselves, which is antethical to their entire existence. Forgiveness therefore is poison to them. To show them love and understanding is to drive them away, which is sad, because in true forgiveness they could be saved.
All they have to do is apologise.