Who is Mélisande?

Mélisande is a character in “The Port-au-Prince Marriage Special.” She is a young woman employed by the narrator to take care of the narrator’s son. After Mélisande is diagnosed with AIDS, she claims that she has never had sex and has never used hypodermic needles. However, the narrator eventually discovers that Mélisande had a sexual relationship with a foreigner (potentially a guest of the hotel) who had falsely promised to marry Mélisande