Nero's personality matches his dark powers. He is the opposite of his older brother, Weiss: quiet, brooding, impassive, and unemotional. Because Weiss is his only family and has always treated him well, Nero harbors an obsessive love for him, almost to the point of worship. Although he is mentally unstable, having been created through unethical bioengineering and human experimentation, he is among the more levelheaded of the Tsviets. Nero can manipulate and manifest darkness.