Marc's best friend is Amanda. The two share spiteful fun in teasing Betty (and others). Marc supported Amanda during her secret relationship with a straight designer who publicly pretended to be gay to help his career in the fashion industry. Marc supports Amanda in her various personal issues, including her discovery Fey Sommers is her birth mother, the search for her birth father, and Amanda's capitalization on the 15 minutes of fame that being Fey's love child gives her. Despite their frequent participation in mean-spirited antics, Marc and Amanda sometimes encourage each other to act morally. For example, Marc encourages Amanda to hand over the letters and perfume for presentation at Claire Meade's murder trial, evidence resulting in Claire's exoneration.