If you go by semitic mythology "Lucifer" as Christians insist on referring to the archangel Samael, was exactly that an angel.
God apparently created three races of beings The Djinn first who where creatures of dust, they had no free will but did have magic, they immediately abused it and so were cast out of heaven in to the pit of fire, secondly the angels who were made from fire, they had no freewill and no magic but who were brave and strong, however they were also willful and some gained freewill by becoming jealous and envious when god created humans from water and air and was so delighted by them that he gave them the earth to live on.
The Angels were ordered to serve and protect the humans and Samael saw this as a slight against his people since they the angels were stronger, more beautiful and immortal, why did god love the humans more?
When god warned him to know his place, Samael lead a rebellion of one third of the angels against god, but were defeated by the Angel Michael.
Samael and his hoard were thrown out of heaven and in to the pit, where they drove out the Djinn and made the pit of fire their own.
In a rage god decreed that Samael would become the first Satan and would be allowed to try and tempt man to sin and away from god, if they succeeded in this the spirits of such men were theirs to consume, however they could not kill people this was known as the rule of gold.
The now homeless Djinn could go to earth but could not use magic against man, but if trapped by men the Djinn must obey them as slaves and must serve the spirits of men as pets. Though the Djinn too were subject to the golden rule, if men were greedy and asked too much of the Djinn they were allowed to deceive humans in to destroying themselves. For example if a man asked for a mountain of gold, the Djinn could give it to him all at once in one big nugget that might crush him to death. If a man asked for his pain to stop the Djinn could turn him to stone.
Man alone can repent, because he or she has freewill by nature and must earn eternal life.
The Djinn and the Angels were blessed with eternal life and paradise, so had no motivation other than greed and sin to desire freewill and so can never repent and never be forgiven for going against their nature