Neania, also called Naenia or She Who Harbors Death, serves as a significant antagonistic entity. Her true nature is the Malnomen of Queen Faustina, the first vampire of the crimson moon, making Neania a manifestation of Faustina's corrupted true name. She exists independently yet remains intrinsically linked to the vampire queen's being, emerging from Faustina's deteriorated state under unclear circumstances.

She typically appears as a shadowy, ethereal figure marked by glowing eyes—one visibly cracked—and an unnerving smile. Her form constantly wavers and emits particles of white energy. When stabilized, she manifests as a young woman with long white hair and large, round eyes, mirroring Queen Faustina's appearance, often depicted nude with hair covering her body.

Neania possesses a singularly malicious personality, lacking all empathy and focused exclusively on hunting the true names of vampires. She views others, including powerful figures like Noé Archiviste and Chloé d'Apchier, as mere playthings or tools to manipulate. Her interactions involve psychological torment, exploiting victims' deepest fears and desires through tailored hallucinations to break their will and acquire their names.

Her primary abilities center on mind manipulation and true name alteration. Neania invades vampires' minds, sifts through their memories, and projects vivid auditory and visual hallucinations targeting their vulnerabilities. Upon obtaining a true name, she corrupts it, inflicting Malnomen. This disease warps body and soul, driving vampires into uncontrollable bloodlust and insanity. Her power also destabilizes reality when threatened, causing spatial distortions and environmental collapse, as witnessed in Gévaudan.

She operates as a core member of Charlatan, the mysterious organization facilitating her creation of curse-bearers. Neania commands other Charlatan members, such as the Plague Doctor, though her exact relationship with the group and their ultimate objectives remain undefined. Her actions directly oppose Vanitas's mission to cure Malnomen, placing her in constant conflict with him and his ally, Noé.

Key narrative involvements showcase her methods and impact: she corrupts Thomas Berneux, transforming him into the Malnomen Loup Garou while viewing him as insignificant; she psychologically torments Louis de Sade, residing within him until his despair culminates in his transformation and death. Her most significant confrontation occurs with Chloé d'Apchier in Gévaudan. Chloé attempts to trap and kill Neania for corrupting Jean-Jacques Chastel, but physical contact triggers Neania's reversion to Faustina's form. Faustina forces a kiss onto Chloé, forcibly jumpstarting her Malnomen onset and triggering catastrophic reality-warping across Gévaudan. Neania then reverts to her shadow form and departs to continue her hunt.

Neania frequently fixates on Noé Archiviste, expressing a twisted fondness and repeatedly demanding his true name as an intriguing target. She also taunts Vanitas with personalized visions during manifestations. Her name derives from Latin roots associated with funeral dirges, spells, and trivial tunes, reflecting her connection to death and enchantment. It also references Nenia Dea, an ancient Roman funeral deity, and a genus of moths.