He was a Choir Master, a shining Star, most Beautiful/Handsome Creature ever(created/made from every Precious Stone), walks on Fire unharmed, was a Cherubim(Angel with 2-edged Sword, too powerful than the others except from Arch Angels), gifted with Wisdom & Intelligence. He is by name "Lucifer," was later renamed "Satan."
Satan knowing that he had all these qualities, felt pride within him.
His Fall began when "Man" was to be created by the "Us(Three GodHead, God as the Engineer, Christ as the Architect, Holy Spirit as the Builder)" led the plan without him/Satan being called.
God's plans for Man included that Angels though above man, are meant to serve Man cos Man is an Image of God.
When the 1st Man was to be created, Angels were told to serve him but Satan refused cos he felt Man should serve him instead. That moment, he thought in his mind that if God insists, that h

... Having thought that, & God as the Creator saw his heart, & gave him Grace to repent but he wouldn't repent.
Satan went telling his fellow Angels that God is not Merciful that if they doubt it they should try God. With deceit, 1/3 Host of Angels planned to make Wars with their opponents. Thank God, He(God) had Angels(the 7 Arch Angels which Michael was the head) greater than others; fought them in the Name & Authority of God. And threw them down to Earth(both in air, land, oceans, etc). They were from that day named "Demons."
Satan with his thoughts, made his Seat high on Earth just as he wanted to be the Most High. Insisted that Man would serve him rather than him serving Man, that he decieved the 1st Man created. He/Satan went into Worship(Churches) for it's the easiest way to get Man to serve him.
"Brimstone in the Hell Fire is meant for Satan(knowing Satan was made of precious stones, will be destroyed by another precious stone unknown to him)."
SUMMARY:
Read on Isaiah 14:11-20.
To the Demons! Between God & Satan,who is Merciful?

lies