Sandi Cosway is Antoinette’s half-brother, born to Alexander Cosway and a “very fair-coloured girl” from a “very respectable family.” Given that he only makes one brief appearance early in the novel, he remains an enigma as other characters offer different descriptions of who he is and the status of his relationship with Antoinette. Daniel originates many rumors about the pair, suggesting that Sandi and Antoinette were sexually involved prior to Rochester’s arrival, and Amélie even recalls hearing that the two had gotten married. While these may be the most detailed mentions of Sandi in the novel, both Daniel and Amélie are so biased against Antoinette and her family that their assessments seem unreliable. 

Antoinette’s perspective also becomes increasingly clouded as the novel progresses, but her three mentions of him offer more meaningful hints about who he is. During their first interaction, Sandi chases away two bullies who harass Antoinette on her walk to the convent. This brief scene establishes Sandi as a protector, someone willing to risk his own physical and social safety to help a distant family member. The gossip surrounding Antoinette’s mother and the destruction of their home at Coulibri does not deter him. Later, Antoinette off-handedly tells Rochester that Sandi taught her how to throw stones, and this detail further emphasizes the idea that he looks out for her. Especially considering the fates of both her mother and Aunt Cora, Antoinette’s memories seem to imply that Sandi stepped up to ease her feelings of loneliness. Rhys ultimately leaves the exact nature of their relationship a mystery, failing to elaborate on the significance of the “life and death kiss” that they share. This ambiguity reflects the fact that Antoinette never has an opportunity to truly explore what a real relationship with Sandi might look like. Instead of pursuing a life with someone she genuinely cares about, cultural expectations about race, gender, and money force her into Rochester’s arms. Sandi represents the love and support that Antoinette could have had if she were free to make her own choices.