Leonard Schteinberg serves as a soldier in Earth's military forces during the war against the hostile Apocalypse aliens. Haunted by failing to save his younger brother from death, this trauma shapes his motivations. When encountering new recruit Jonathan Tyberius, whose resemblance to his deceased brother is striking, Leonard feels a protective instinct fueled by unresolved guilt.

His relationship with Jonathan evolves past this initial dynamic. During training, Leonard displays strong integrity, rejecting the corrupt authority of their superior officer, Continental, who sexually preys on subordinates. Leonard confronts Continental to protect Jonathan from his advances and abuse of power. After Continental rapes Jonathan, Leonard retaliates by violently castrating him. This act of vengeance results in Leonard's immediate transfer to the front lines as punishment, separating him from Jonathan.

Before deployment, Leonard spends a final night with Jonathan. He explicitly clarifies his feelings are now for Jonathan himself, separate from his brother's memory. Leonard also exacts a critical promise: should he be captured and assimilated by the Apocalypse aliens—a fate involving loss of autonomy and integration into alien biomechanical entities—Jonathan must kill him to prevent eternal suffering.

Leonard's subsequent capture by the Apocalypse fulfills his worst fear. Assimilation transforms him into a monstrous entity under alien control, embodying conscious torment. During a battlefield confrontation, Jonathan upholds his promise, driving a killing strike into Leonard's chest. In his final moments, Leonard seizes one last shred of autonomy, pushing Jonathan to safety before his body is destroyed, ensuring Jonathan's survival.