itch.io

rush will be at the first block of the high sec area (the red tile in the cell blocks where you sleep) once you arrive as said from the previous comment an option "look for rush" will appear after. you can than either fight him or offer your body to deal with him

(don't know if offering your body does much as i mainly just cracked his bones to deal with him)

if you beat him enough times you can permanently deal with him so you don't have to deal with him