9S(Infected)

Single blade.

9S has the appearance and voice of a teenage boy. He has short, snow-white hair that is neatly styled, and removing his standard blindfold reveals pale blue eyes framed by rather long eyelashes. His outfit consists of a trench coat with the YoRHa emblem embroidered on the hem, split at the sides to allow for more movement, with large cuffs fastened with belts, a pair of shorts, knee-high socks, and a pair of combat boots also fastened with belts, all dyed black in the same leathery texture that all YoRHa units seem to have on their clothing. For accessories, he wears a black choker around his neck with a square with an X attached to it, black gloves, and his signature fanny pack. His eyes glow in a red color because of the Logic Virus, his synthetic skin and features begin to decay, glitch, and lose their color.

9S goes on a warpath to kill every last machine. Blinded by grief and hatred, he tells himself that there is no meaning to anything the machines do as he goes through the Resource Recovery Units, despite knowing the opposite. This cognitive dissonance becomes even more pronounced when he discovers that the YoRHa black boxes are made from the cores of machine lifeforms - something he denies outright. His hatred of the machines is so great that he destroys a helpless child core without hesitation, despite the meek protest of Pod 153.

After the death of 2B at the hands of the logic virus and A2, 9S's darker side overshadows his former personality. His change in demeanor is noticeable as soon as he wakes up in Routes C and D ; he is calmer and more subdued as he quietly asks, "Where's 2B?" Overwhelmed by grief and anger, 9S's mission objective changes from simply fighting the enemy to taking revenge on them and A2. His mental state suffers greatly during this time, and Pod 153 becomes increasingly concerned about him as he continues his quest to enter the Tower. Gradually, his quiet rage grows louder and louder until it erupts at various points; from telling machines to shut up to breaking into a fit of laughter after stabbing the core of a Resource Recovery Unit he thought was 2B, his behavior becomes increasingly self-destructive and dangerous. Concerned for him, Devola and Popola plead with him not to die alone - a plea that falls on deaf ears.