Samantha and her twin brother Dane were born to the Larkspear family in Atlanta. After finishing her training she and Dane attended the Scholomance and graduated as Centurions. At some point, presumably during her time at the Scholomance, Samantha and her brother met and befriended Zara Dearborn, sharing her views on Downworlders and the Cold Peace. Samantha and Dane became members of Zara's inner circle, and members of The Cohort.
Samantha often bore false witness to Zara's claims of heroism. She signed off on many reports that depicted Zara as an amazing Shadowhunter.
In 2012 Samantha and her brother were dispatched to the Los Angeles Institute as part of a team of Centurions. Samantha was tasked with running interference with Diego Rosales and Cristina Rosales for Zara, who didn't want Cristina "stealing" her fiancé. Samantha offended the Blackthorn family when she spoke with disgust about Magnus Bane and Alec Lightwood's relationship, and insulted their brother Mark Blackthorn by calling him a half-breed.
Samantha is an ignorant, mean-spirited girl. She shows great disdain for Downworlders and Shadowhunters "tainted" with Downworlder blood or relationships. She is quick to insult the subjects of her disdain but becomes upset when they fight back, as seen when she snapped at the Blackthorns not to make her feel bad after she insulted Mark and his siblings responded angrily.
Samantha, like her brother, has a thin, whippety face with pale skin and straight black hair.
- Lord of Shadows (first appearance)