Who is Gabrielle Deschain?

Gabrielle Deschain is Roland's mother and Steven's wife who died at Roland's hand when he was tricked by a witch, Rhea of the Coos. Gabrielle had made Steven into a cuckold by becoming the consort of Marten Broadcloak, the court magis and Steven's chief adviser who abandoned her. She spent time at the retreat in Serenity, and Everlynne recognizes Roland as Gabrielle's son and gives him a letter that his mother left for him. In the letter, Gabrielle admits that Steven begged her to stay at Serenity lest she die at her son's hands, but she must return to Gilead because Ka demands it. Gabrielle ends the letter by forgiving Roland and asking for his forgiveness in return.