She is a Worker Drone improperly disposed of, resulting in the A-S mutating inside her and using her body as its own. Under the Solver's influence, Cyn is responsible for many major events, from the Elliott manor massacre to the deployment of Disassembly Drones to Copper 9.

Cyn presents herself as the smallest Worker Drone in Elliott Manor. She wears a black-gray maid dress, a white apron, and a white inner dress with a large bow tie. There are two buttons below the bow tie. She has silver hair and two straight-down twin tails, each with a hair band on the lower end. Also, a big black bow is at the back of her head, as is a maid's crown.

Reference some lines from here: https://www.youtube.com/watch?v=0X1pio0mdhQ