Tristan’s step-mother and Meliadus’s second wife in La Tavola Ritonda. The daughter of King Bramo, she is unnamed in previous versions of the legend, including the Prose Tristan.
She hated Tristan because he stood to inherit Lyoness ahead of her own son, Allegreno. Her first attempt to poison Tristan ended in failure when Meliadus nearly drank the poisoned tonic himself, and Agia had to confess her treachery to save her husband. Meliadus sentenced her to die, but the generous Tristan intervened and his father spared her.
She tried to murder Tristan a second time, but a nurse accidentally served the potion to young Allegreno, who died. Meliadus did not punish his wife, but he never spoke to her again.