Lucifer, originally named the Angel of Light or Morning Star, was God's most favored angel, renowned for supreme beauty and power. His belief in his own perfection bred arrogance and rage when God chose humanity as His favored creation. Lucifer rallied an army of angels and rebelled against Heaven to usurp divine authority. Defeated by the archangel Michael, he was cast out of Paradise and banished to Hell, where he seized control as its ruler, presiding over the damned for eternity.

During Dante's Crusades, Lucifer orchestrated a bet with Beatrice, Dante's fiancée. The terms promised Dante's safe return if he remained faithful, but claimed Beatrice's soul if he proved unfaithful. Dante's infidelity led Lucifer to claim Beatrice upon her death, taking her soul to Hell to become his bride. He exploited her purity, intending to corrupt her through a demonic marriage ritual, believing her unspoiled spirit could help him escape his infernal prison and challenge Heaven anew.

Lucifer manipulated Dante's journey through Hell, appearing as a spectral shadow to taunt him with flashbacks of his sins, including his betrayal of Beatrice and wartime atrocities, aiming to break his spirit. Upon reaching the Circle of Treachery, Dante encountered Lucifer imprisoned in Lake Cocytus, a frozen lake formed from the fallen angel's tears. Lucifer manifested as a colossal, three-faced demon trapped in ice, his bat-like wings generating icy winds that perpetuated the ninth circle's frozen torment. In this form, he chewed eternally on history's arch-traitors—Judas Iscariot, Brutus, and Cassius—symbolizing ultimate treachery.

Dante's attack on Lucifer's massive form shattered the Chains of Judecca, freeing the fallen angel. Lucifer split open his own stomach, revealing his true, agile form: a corrupted, humanoid figure with torn wings, massive horns, and goat-like legs. Wielding a flaming sword, he commanded fire-based attacks, teleportation, and flight. Lucifer revealed Beatrice was merely bait to lure Dante, whose soul—blackened by sin yet strong enough to endure Hell—was uniquely suited to break the chains. Historical figures like Alexander the Great and Lancelot had failed due to insufficient impurity or strength.

During their battle, Lucifer displayed his nigh-omniscient intellect, teleportation abilities, and immense physical power, including shockwaves and fiery assaults. Though Dante overpowered him, Lucifer disclosed that Dante, being deceased, could not leave Hell under divine decree. Dante summoned absolved souls, who used Beatrice's holy cross to force Lucifer back into his giant form and reimprison him in ice. As Dante departed for Purgatory, he discarded his chest tapestry, which transformed into a serpent—a symbol of Lucifer's temptation—while his echoing laugh hinted at an unresolved escape.

Lucifer's personality melded cunning intellect with profound pride. He employed Faustian bargains, psychological manipulation, and calculated trials, such as using Beatrice's wager to ensnare Dante. He exhibited a twisted sense of honor, punishing only the "impure" while claiming moral justification. His dialogue emphasized contempt for humanity's flaws and resentment toward God for favoring mortals over angels. He viewed human free will as the catalyst for sin's proliferation, asserting that while he introduced sin, humanity spread it "like a plague."

His powers included immortality, invulnerability to conventional harm, mastery of ice and fire elements, storm generation, and reality manipulation, such as igniting forests via incantations. He could project a shadow form across Hell and Earth, displaying superhuman strength and the ability to assume disguises, including Dante or God. His true form enhanced these abilities, though holy relics like Dante's cross could temporarily weaken him.