Usiel is a arch angel as well the commander of the angelic Seventh Legion that fought in the End War but now remains stranded and diminished on Earth. Now the disheartened commander struggles against undead angels and demons under the command of the Deadly Sin, Lust.
A powerful and dedicated leader, wielding a massive bell as his weapon, Usiel leads the Seventh Legion in an ongoing struggle for survival and retribution on Earth during the demon's beginning reign over the planet. Envy, as a Watcher, states Usiel to be a honorable warrior.
However, years of struggling and the recent emergence of the Seven Deadly Sins, Usiel has become uncertain if his forces can hold out against the demons. Worse, undead angels and demons have risen to cause more problems for the angels, forcing them to take shelter in an abandoned shipyard.
Usiel originally fought the demons on Earth when the End War began prematurely, leading the Seventh Legion valiantly. Despite this, the angel forces failed to defeat the demons, causing them to be stranded on the shattered Earth when the White City closed its gates.
Usiel attempted to continue the fight but the growing losses of his troops and the recent return of the Seven Deadly Sins, began to plague Usiel and his men with doubt. Worse, Lust used their newly acquired abilities to raise the dead angels and demons as her servants, forcing Usiel and his men to fight their own fallen. The continued losses mounting, Usiel and what remained of his Seventh Legion were forced to take shelter in an abandoned and decrepit shipyard, just outside of Lust's domain.
The angel commander and his forces would soon encounter the hunter of the Sins, Fury, during one of his legion's hunts for Lust's undead. The Black Rider was determined to find answers and justice for the murder of her steed, Rampage, as it was an angelic weapon that killed him. After a tense battle between Fury and his forces, the two agree to peacefully discuss things. Though Usiel is adamant that his forces do not wish to make an enemy out of the Riders, thus denying any knowledge in Rampage's death. Despite the severe wariness he has towards the Black Rider and his men's protests, Fury and Usiel agree to work together in order to bring down Lust. Usiel also gives Fury the ancient angelic crossblade, Salvation, as a show of good faith and support.
However, Usiel makes a surprise intervention just as Fury confronts and battles with Lust, vowing to kill the Sin for the defilement of his angelic brethren. Unfortunately, Lust entices Usiel to defend them with his desire to return to Heaven with the Seventh Legion whole and victorious, turning him against the Horseman.
Battling against the brainwashed angel and the Deadly Sin, Fury manages to subdue Usiel but remains alive as she finishes off Lust. Usiel remains at Fury's mercy but the Horseman decides to spare him, knowing that he is innocent in being susceptible to Lust's words. Despite her Watcher's protests, Fury and Usiel agree to form an alliance for now but the two remain rather wary of each other.