Chrome is a gear who was found in a ruined facility by Roue, who subsequently activated him. Once activated, he lacked a base program. Afterwards, Chrome lives with Roue and Zett, learning about both of them.
Later on, a rogue combat droid appears that threatens Roue's life. When it does, Chrome decides to protect Roue as his base program, shedding his bulky body for a human-like one. Once Chrome asks about the base program, Roue accepts, making him her guardian.