Belial is ?highly popular story series originally published in the Fanfics forum on SDN. The chief author is Stuart Slade.
Like all "angels, demons, and deities in The Salvation War universe, the demon lord Belail is not a supernatural being, but rather an extradimensional alien who attempt to place Earth under their dominion in 2008, after God decides to end the world and commands all humans to die. Humanity ignores this message until demonic heralds arrive on Earth to declare Satan's dominion over the Earth, only for both the heralds and later Abigor's demonic army to be easily crushed by human military forces. This results in a human invasion of hell itself. In the chaos of this invasion, Belail, the lord of a backwater region of hell, finds a way to gain Satan's favor by finding a way to strike back at humanity. Belail lies to a group of damned souls, stating that humanity is losing the war (when they are in fact winning decisively), and only those who aid hell will be freed from their eternal torment. He asks for the name of the leading human industrial center. A human who died in the late 19th or early 20th century gives him the name of Sheffield, England, a major industrial center at the time. Belail uses arrays of wires, believed by the primative demons to be shrines which increase the natural portal generating powers of nagas (in actual fact, the enhancing effect is because of the wires channeling the energies of the nagas), a race of snake-like demons, to teleport a volcanic eruption onto Sheffield. The portal opens over the city, pouring lava down onto it and killing thousands. To the shock of the demons, however, this does nothing to human industrial capacity. Indeed it has no impact, save for infuriating humanity and causing them to launch a bombing raid on Satan's fortress in the city of Dis, which Satan only survives as he is not in the fortress at the time.
Belail assume that there must be a second center of human industry, and finds another name: Detroit, Michigan. Using the same method he used to attack Detroit, he causes severe damage and casualties a second time, though the portal is eventually closed using a human-developed device. Aided by intelligence gained from Abigor, who has by this time defected to the side of humanity after witnessing the power of human tanks and aircraft, to locate Abigor's base. A squadron of US B-1 bombers launch an air raid against Belail's fortress, destroying it, though yet again Belail survives.
Belail is soon after forced to flee hell after US military forces kill Satan himself using missiles fired through portals, and Abigor takes over in a coup. Belial continues to resist for a short period, but the remains of his fortress are soon captured by human ground forces.
Belail flees into the domain of his former enemy, Yahweh, who allows him to stay as a refugee in spite of the past hostilities between God and Satan. When God discovers a plot against him from within heaven itself, he puts Belail in charge of designing prison camps intended to torture his enemies. Eventually, however human forces invade heaven itself, and inflict a pair of crushing defeats on the Angelic Host, with one force destroyed using nuclear weapons. Realizing the magnitude of the threat, the archangel Michael launches a coup against God and literally kills him, before allowing human forces to enter the Eternal City, capital of heaven, unopposed. Belail, however, outlives both Satan and God, and escapes yet again, presumably to some uninhabited region of hell.