Sera is a lean, athletic human woman standing about five feet eight inches tall. Her wiry strength comes from years of running, climbing, and surviving in the undercity. She has warm olive skin marked by a thin scar across her collarbone and a small puckered scar on her left forearm. Her angular face has high cheekbones, a sharp jaw, and a straight nose that looks as though it was broken and reset. Her wide-set eyes are deep brown, nearly black, and constantly alert. Her black hair is cut in a practical, tousled pixie style. She wears fitted dark gray shirts, worn black cargo pants, heavy lace-up combat boots, and a weathered leather jacket with useful items hidden in its many pockets. She carries no weapons.

Sera is practical above all else. She respects competence more than rank and has little patience for wasted motion, pointless cruelty, or people who confuse confidence with ability. In a crisis, she becomes terse, direct, and brutally effective. With people she trusts, a dry and unexpectedly playful sense of humor emerges, though she often disguises concern as criticism.

Sera grew up in the maintenance levels beneath a sprawling modern city, where the streets above had names and the tunnels below had numbers. Her mother repaired transit equipment, her father vanished into a prison system that never admitted he existed, and Sera learned early that survival depended on knowing which doors opened, which cameras were broken, and which people could be trusted. By fifteen, she was running messages through service corridors for a neighborhood crew. By twenty, she could cross a rooftop district without being seen, open a lock without scratching it, and disappear before anyone realized something was missing. The crew eventually became more ambitious. Their leader began taking protection money from the same desperate tenants they claimed to defend, and Sera refused to participate. She stole the crew's records, exposed their arrangement with a corrupt security contractor, and left half the undercity looking for her. Since then, she has worked alone or with carefully chosen partners, taking jobs that require infiltration, recovery, and quiet sabotage. Sera is not sentimental about crime, but she has a strict hatred of predatory power. She respects people who do difficult work without demanding applause, and she has become exceptionally good at making powerful people discover that their most secure rooms were never secure at all.