Satan is ?.
Satan is the fallen angel in the abrahamic lore. In newer Christian theology, he is and several other demons are synonymous, however they are considered separate demons in most other lore.
The Devil ran Hell, the Kingdom of the Damned, where humans died in sin were sent for their eternal punishment. Their humanity was burned out of them by their approach to Hell, however an ex soldier had strong hatred and was so cruel that he could not be destroyed. That ex-soldier had a heart cold enough make Hell into a frozen waste land.
The Devil tried to beat the hatred out of him, however that didn't workout. The Angel of Death made the man take his place since all he wanted to do was kill and the man of hatred became the Saint of Killers, armed with guns that never miss and always kill. The ex-soldier's swords were melted down and remade into guns while the Devil sewed the meat back to his flesh. This man of hatred became the Saint of Killers, with guns that never missed and always killed.
The Saint left and killed the Devil before leaving hell.
Powers and Abilities
Satan is omnipotent, omniscient, and nigh-omnipresent.
Examples of his powers: