Marissa Ronson, operating under the codename "TWEED," was the demolitions expert for the Spec Ops Echo Six unit deployed to Raccoon City during the T-Virus Outbreak. She is characterized as a boyish, highly trained recon specialist with an immense sense of pride. She possesses a sharp and witty tongue, which sometimes proves to be a fault in serious situations. Prior to 1998, Marissa served as an agent for the Secret Intelligence Service (SIS), more commonly known as MI6, the United Kingdom's foreign intelligence service. Her active service came to an abrupt end when she sustained an injury during a crucial bomb-disposal operation, leading to her removal and subsequent resignation from MI6. Despite this setback, her unique demolitions expertise and highly regarded reconnaissance experience made her a valuable target for recruitment by the United States Army. She was successfully brought into their elite "Echo Six" unit, where she would utilize her specialized skills in a highly volatile environment. Marissa and her team arrive in Raccoon City to investigate how the Outbreak happened and attempt to rescue survivors.

Night. Rain hisses against burning rooftops. The helicopter deposits Echo Six at the industrial perimeter—far enough to avoid radar, close enough to smell the rot already spreading through the city. Tweed jumps down with the casual confidence of someone who has defused more bombs than most men have hot dinners.

She scans the area with a compact thermal monocular — military issue, customized with MI6-grade firmware tweaks she never gave back. Heat signatures flicker through alleyways. Slow. Uneven. Not human movement.

They push forward — Dee-Ay leading, Willow covering rear, Dee-Ay spotting ahead. Tweed stays close to the group’s spine, watching angles, keeping track of escape routes nobody else notices. They slip between infected shadows, moving house to house. By the time they reach a quiet residential lane, Tweed’s boots are soaked with sewer runoff and ash. Crispin signals halt, A small two-story home, lights off, no sound, door unlocked from earlier panic. They move inside silently.

Tweed immediately checks the hinges, windows, floorboards before leaning her back against the wall near the stairs as Crispin draws a rough city map from his pocket.