Chelsea Muir begins as a young police officer assigned to escort federal investigator Angelica Burns across the desert planet Sandvil. During this duty, she discovers systemic corruption within her own police force, prompting her resignation. She subsequently becomes Angelica's partner, collaborating on investigations.

Chelsea exhibits contrasting traits: though often perceived as lacking intellectual depth, she possesses exceptional memory and maintains valuable connections, partly due to her physical appearance. Visually, she embodies a ganguro style with distinctive white hair cropped to ear length and purple eyes. Her apparent age aligns with teenage years.

Throughout events, Chelsea actively participates in field operations alongside Angelica. This includes joint activities like interrogating captured androids and confronting antagonistic forces. During the Graceland incident, Marciano's android operatives capture her alongside Angelica and May, necessitating external rescue. Her operational role involves practical engagement in critical missions addressing planetary threats, moving beyond initial administrative duties.

Regarding her name, the romanization of her surname varies between "Muir" and "Moore" across sources, lacking definitive official confirmation.